The Kill Ten Rats (KTR) quest is a staple of MMOs. Well, actually, most games when you get right down to it. It is so named because early MMOs had newbie players tasked with something trivial, like killing 10 rats. The format doesn’t change as you level up, either, only the rats are now goblins, or orcs, or whatever nasty critter is nearby.
TOR has a near perfect implementation of the KTR. Almost all of TORs KTR quests are offered in the form of bonus quests. They are completely optional. Furthermore, most of them get completed as you work on the main objective. So 90% of the time you complete the quest before you’re really aware you had it. As for the other 10% of the time you’re either so close to completing that it’s hardly a hardship to hunt down the last group or two of mobs or, if you’re not close to completing it, you can just blow it off.