@QueenVera
Avatars who were created for advertising-purposes usually contain the name of the company that is being advertised. Take a look at the first two avatars under your post. The words BestChange and Aurox are easily spotted. It takes you just a second to enter this into a search engine to see what it is. I would say that 8 or 9/10 companies who are advertising on Bitcointalk require users to wear both avatar and signature if their rank is high enough. If you don't want to search for the ad manually, a click on the sig would take you where you want to go.
And accidentally clicking on an avatar and it taking you offsite to who know where isn’t really that great either
Clicking on the signature can also lead you to God knows where, if the user wanted to.
I think, like some here have touched upon, linking a profile avatar to that persons personal profile page would be a nice feature, but overall pretty unnecessary. I don't think we should be pushing new implementations to the forum.
It is not a feature that we really need in this forum, but it might be worth trying when the new forum gets introduced. Does the new forum software allow such implementations?