I began to hate complicated systems years ago when I had to spend six hours creating a character for Rolemaster under the watchful eye of the GM. When the game started I was killed in the first twenty minutes - I was backstabbed by the GMs fucking NPC assassin! All that time in character creation, wading through books and choices and complicated crap that would make no difference to the character anyway and I don't even get to experience the very reason why I'm in the hobby; playing an RPG.
After that I was loathe to spend any longer than half an hour in character creation. That spread on to the rules themselves. Now I just want simplicity. I want to be able to sit at the table for a four hour session and be able to have the characters ready in the first 30 minutes, spend the next 30 minutes making sure everyone is up to speed on the basics of the mechanics and then the next three hours playing an actual game. Then we're sorted for the campaign.
I don't want complicated character advancement, either. Got points to spend? Levelled up? Right, end of session, ten minutes to spend/choose. That's that, ready for the next game.
I'm over rules - I just want to play and be played!