Until you have a mechanism that guarantees murderers and such are pursued by the guard, you can't afford having auto accept in guild wars and challenges. Because that would make the game not realistic. And a hack n slash heaven. You'll have all these morons that don't even know they're at a MMORPG kicking people's butt in a town where there should be someone protecting the villagers.
PvP is not that important. People make a great fuss over it and even go as far as making it the objective and prime feature of their pseudo-roleplays (that's what I call the concept of "let's have a roleplay today about chesse!"). I've seen it more than once, someone coming around with the "Power Glyph of Doom" and the "Immortal, Unaffected by Guards Slavers Of All" just to have a big fancy war in the end where people fight, people die, people live, people fight, people die, people live and nothing comes out if afterwards. Everything becomes just the way it was before the uberness had settled.
Really people. Some of you just need to expand your perspective of roleplay. Nowadays people "roleplay" fights like I roleplay Sangwa going to the tavern. Vulgar, daily, boring.
When you read a fantasy book you're not just hoping to see fights. You're also hoping to see magic, feelings, surprises and fun.