using the name of a previously banned user may be upsetting to some people/problematic, I don't really see how this would help anyone

Advertisements are one of the main sources of income for sites once they are launched. Without their funding sites would almost certainly not be profitable.

If you have issues with adverts you can always get a job (aside from artist) or buy VIP.

If you visit someone's wall on desktop it tells you how many friends they have. This would be pretty neat as a mobile feature though.