Security on Filesharing for AD users

You are right, it is not possible to define this down to the user level for AD members. That is feature request, which I recommend you to vote for on Serv-U FTP Server & MFT Server forum.

But that is the group and user levels within Serv-U, not Active Directory, right?  If I am incorrect, can you please explain how to do it correctly so that certain users in this Active Directory domain, Active directory group can have all clients available, but anyone else only gets the file sharing client - for instance.

I haven't been able to have it discern between Active directory groups at the same domain/OU/../group   levels within Active Directory.

With the new release 15.1.0 it is possible now to selectively disable and enable File Sharing on global, domain, group and user level with many limits specifically for file sharing on all levels (e.g. enforcement of password, expiration of file share and many other).

We surely are also looking for this Option

Thanks for so many comment and good feedback. This is something we are looking at, check out What We're Working On - Serv-U FTP Server, Serv-U MFT Server & FTP Voyager.