-We already have a functioning in-game option for a party leader to 'oust' any member of the party. If the party leader afks, the group can reform without him. No need for getting booted out of game if afk.

-People remember who was nice and helpful and who was a leeching AFKer. People who consistantly AFK, leech, or are just unpleasant in general, get a bad reputation and ultimately, pay the price. Linkshells drop them/won't recruit them, they have trouble finding parties..etc. Again, no need to have the game punish them.

-Also, there ARE legitimate reasons people go afk. Reasons they communicate to the party and that are okay'd that would maybe extend past the 10-15 minute window you are suggesting. The game can't tell the difference between 'Oh crap guys I'm really sorry but my toddler is puking all over the floor got to afk!' and just silently going afk while others farm coffers for you for 30 minutes.