Characters that *just won't die*! I don't mean bosses, I mean a character that is killed for plot reasons, then revived later for some stupid reason, or no reason at all. It completely kills the drama of the character's death! (Infinite Undiscovery and FFIV I'm looking at you.)
Games that shoehorn in multiplayer that doesn't need to be there. (Every RPG ever that has tacked on multiplayer/coop that is rushed, broken and/or pointless...)
In a similar vein, games that have an *awful* single player campaign because the devs spent too much time on multiplayer.
Bad audio balancing, bad translations, awful voice acting... I like my ears and my speakers the way they are thanks - working!
Unskippable cutscenes right before a boss fight. Being forced to watch the same, usually very long, scene over and over again just adds to the rage of losing in the first place!
Boss fight runs, where you have several fights and no ability to save in between. This is tolerable if it's done right; if it's multiple stages of the same boss or the earlier fights aren't full blown boss fights, but when it's three or four full, separate boss fights with areas between them? That's easily hours of gameplay in an RPG and I don't want to do it six times over because something got a cheap shot on me! (Infinite Undiscovery final dungeon I'm looking at you *again*! Three boss fights and two large mobs of enemies in a row, and I always died to the mobs of normal enemies because of the damage animation.)
Games that let you get into a state where you have to restart. Mostly dungeons that lock you in, but there are other culprits of this. (Blue Dragon Plus, FFVIII... I know I've played lots of others but can't remember them now...)
Sewer levels, mystical forests that are designed to get you lost, teleporter-based dungeons, final dungeons that are huge towers of some kind and any large area that copy-pastes enough art that you can't orientate yourself and navigate properly. (Infinite Undiscovery, Pokemon R/B/Y, Shadow Hearts, the entire Shin Megami Tensei series...)