While it's my favorite genre, I have to acknowledge there are many persistent problems with role-playing games. Having these problems doesn't ruin a good game and solving them doesn't save a bad game but either way, it's a real kick in the teeth to encounter them.
The weakest part of many role-playing games is the first hour or so. Why? Because they take so damn long to get started. Developers decide they have to ease the players into the game so they begin the game at the main character's military academy or peaceful rustic hometown. The latter is the worse of the two, by far. An RPG that begins in a small country village always starts something like this: "Hello child, can you fetch me some apples? Don't forget the festival is in town today! Your rambunctious friend said he'd meet you there! OH MY GOD MASKED MARAUDERS ARE BURNING THE VILLAGE, SAVE YOURSELF!!!" Examples that come to mind are Fable and Neverwinter Nights 2.
All I'm asking is that you start the game in a way that grips the player quicker. Final Fantasy 7 begins with Cloud attacking a power plant - good! Mass Effect begs with Shepard answering a distress call on a nearby colony world - good! I didn't like NWN2's opening but the Mask of the Betrayer expansion starts with the protagonist waking up in the middle of a tomb thousands of miles away from his home - much better. I understand that players need to be taught how to play and developers think they need to integrate that learning process into the actual game somehow but it's really not that obtrusive to just have a window pop up in the corner of the screen and tell us the controls. It's not distracting - we're used to that sort of thing from other genres by now.
Oh, and another thing about beginnings: don't fill the first zone of a game with characters who answer questions that the main character would clearly know the answers to already. Way too many RPG's allow the player to walk around asking the main character's friends and family, "Who are you? Where am I?" Instead of being disturbed that their relative/friend has suffered brain damage, these other characters then reply, "Are you feeling okay?" or "Heh! You must be sleepy!" before launching into an exhaustive information dump. Why do we need to have everything spelled out for us? Is it that hard to figure out that the character who lives next door to the protagonist, is the same age as him, and wants to go to the carnival with him is his friend?
No, I don't want to deliver your fucking letter to Lady Rottencrotch. If you want to give some fresh bread to Griswold the burly innkeeper, go do it yourself or find a courier who isn't wearing platemail and carrying a flaming sword. The original Baldur's Gate did a lot of this but so did many, many other games. A quest that consists of walking up to one person, receiving an item, then walking up to another person and handing them that item isn't challenging or entertaining the player - it's testing them for a learning disability.
The only good thing about the genre being riddled with these stupid quests is that it sets players up for a surprise. For example, there's a quest in Knights of the Old Republic where you're asked to deliver a box to a crime lord. Sounds like a basic courier quest until you try to open the box and you're promptly sucked into it. Also, I don't mind these quests if they're driving the plot in some way rather than being filler. The steampunk RPG Arcanum begins with a zeppelin crash. A severely wounded gnome crawls from the wreckage and hands a ring to the only other survivor, the player. He then tells the player to give it to "the boy" before dying. This sort of thing is the exception rather than the rule when it comes to errands, though.
Combat for a role-playing game can come in many forms it should adhere to one principle: the player character(s) should gain abilities as the game progresses and so should the enemies. That seems simple enough but apparently not. This has gotten worse with the advent of "action RPG's" and the transition from turn-based to real-time combat. Combat in these new games feels like a brawler or a FPS except with less buttons and the enemies just blindly run toward you.
Fable comes to mind with this category because melee combat consisted of an attack button, a block button, and a button to break your enemies' blocks. There's nothing wrong with real-time combat but if you're going to make your combat like an FPS or a brawler, at least have it play like a half-decent FPS or brawler. Combat might not be as central to a role-playing game's success as it is for an action game but it's still the primary way players are challenged. While a game can skate by with crappy battles on the strength of its other features, tiresome battles will limit the game's ability to appeal to anyone besides hardcore RPG fans.
When bragging about the size of the game world they created, developers will usually say something like, "It takes two hours for players to run from one end to Jerkoffia to the next!" Which begs the question: why the hell would I want to run for two hours in a video game? Luckily, many developers have recognized how un-fun commuting to a game is and now include options for fast travel in their games. Usually they'll have some sort of ferry to get you from city to city - very thoughtful RPG's even include mass transit in the largest town so you can get from one end to the other instantaneously.
This particular problem is bigger in MMORPG's because they're subscription-based. The more time the developers can get you to spend on travel, the longer you'll play and the more money they'll make. Either that or they all really love jogging, because that's what you'll be doing until you scrape together enough money or levels to buy some sort of mount. In World of Warcraft, you buy a land mount at level
It's no fun to fritter away hours jogging around the game map, and it's even less fun to spend time rummaging through your character's backpack. I'm not talking about games that have detailed inventory systems and require your to customize your equipment; I'm talking about games that give you no assistance in organizing the loads of crap you collect over the course of the game. You know, the games where you have to scroll for ten minutes just to find a health potion (or whatever weird name it goes by in this particular game).
Mass Effect is a good case study for this subject because its inventory system is really good and really shitty at the same time. You can break down any unwanted items into Omni-Gel that you can then use for repairs and lockpicking. Unfortunately, you'll get about ten thousand unwanted items and items of the same type don't stack so you have to flip through every item individually. Eventually you run out of bag space and you'll be prompted to discard some of the items that just dropped...except the game doesn't display the stats of these items that just dropped so you're just trashing shit at random. Obviously inventory issues aren't nearly as important as other game features but it's disappointing to see a contemporary game as good as Mass Effect have an inventory interface clunkier than a Super Nintendo RPG.