There are MMOs that stick to the conventions and MMOs that work around them, but we all recognise the conventions when we see them. They make up much of the vocabulary of an MMO and fuel the memes that go around: we all recognise the likes of Kill Ten Rats and Looking For Group. Conventions are those features that we expect to find in an MMO of a given genre, whether we like them or not.
But given the opportunity, which one of the various MMO conventions would you banish to the infernal regions, never to return?
There are just so many to choose from. Quests where you kill X amount of Y creature, or collect randomly dropping pieces of its anatomy? Missions where you escort the balsawood NPC to safety? Monotonous resource gathering? Endgame raids? The tank-dps-healer trinity? Long travel times? Elf-orc-dwarf mythologies? Epic loot? Gear covered in so many spikes you could use it for a weenie roast?