- Morrowind's levitation (was also useful in discovering secrets and reaching high/floating areas)
- Quests like Arcanum's gnome conspiracy one. Not every quest should leave the player saving the day and solving the problem.
- Arcanum's backgrounds. Beyond their allowance of extreme builds from the get-go, they offered the player great ideas ideas for how to roleplay and what sort of personality the character likely has. I don't really enjoy RPGs where I feel little attachment to my character (DA:O, Skyrim, BG) or very little motivation due to the generic or poorly-written plot.
- Reasonably sized pool of recruitable NPCs. I never really liked how in most RPGs with permadeath, losing a party member equates to "lol reload" unless you want to continue the game gimped. But I also dislike the more modern system of party NPCs being unable to die. Jagged Alliance solves this with a large selection of mercenaries to hire, meaning that losing one isn't the end of the world (though it's certainly something you don't want to occur often, due to both the expense and the morale loss). All these mercenaries being interesting BROs and having strong opinions of the other mercenaries (with in-game repercussions) was just the icing on the cake.
- Firearms not sucking. Thank you Fallout 1 and 2. Though melee catches up again in the late-game with things like power fists and super sledgehammers, by-and-large bringing a knife to a gun fight in early-to-mid level Fallout (which is when the combat is at its most fun, before things turn >95% accuracy eye attack<) gets your head (literally) blown off. Sadly, if an RPG includes firearms chances are that they completely suck. It's even worse if the setting is modern or futuristic yet guns are peashooters that have 1/5 of the damage potential of a katana. Darklands also receives an honourable mention for guns acting reasonably historically for the time; they inflict strong damage but their horrendous reloading rate means they are pretty much only useful for an opening volley followed by closing to melee.
- Fallout's power armour. It's not easy to acquire but boy when you do you are a walking god that can kick the ass of anyone without serious firepower. It's a great feeling seeing those gangsters trying to cut you up or punch you with brass knuckles while you laugh it off without taking a scratch. It was also a nice touch having NPCs recognise that you're wearing it and addicts thinking they're hallucinating while others cower in fear. Power armour felt a lot more underwhelming in FO3/NV due to it just being an incremental improvement over the previous best armour. Obviously this isn't applicable to every setting but more games should include game-changing items like this (instead of incremental upgrades of Steel Longsword -> Steel Longsword +1 -> Steel Longsword + 1 of Fire -> Steel Longsword + 2 of Fire). Acquiring a set of plate armour in a early medieval setting is comparable and should make the combat feel fundamentally different.