Well, this might have been up a few times before (I don't know) but I think you should be able to delete all the comments fast... (the mods and admins can faster than we).....
Where do you mean? On our profile pages? If I understand correctly, you want to be able to select all the comments on your profile with a single click, and then delete them. Am I right? I don't know if it's a good idea, I mean, I don't see that many people who keep their profile clear of comments... I think it's better just to delete them as they come, but it's just my opinion.
I think it's a good idea, like if you get a lot of spam messages on your profile, you can just select the messages you want to delete, hit delete, and all of them delete at the same time.
Right now you have to keep waiting for the page to reload after deleting one comment.
Is it a laziness thing? If you don't like the comments, delete them individually. There's no sense in asking developers to code something that may take a few days of work, when it'll take you a few hours to delete comments. If you're talking about comments on games, that would be super nice! But it would encourage one time spam, then deletion -- sneaky spammers would then be created.
Then people will be wondering: "What the hell?! I lost a bazillion points?! Oh right, I shouldn't have chatted..." :P