UserVoice is definitely not well implemented. I agree with many of these, but I may be able to help with one.
For the "Cannot delete or reactivate a user once created," you can change their role to "none," which will lock them out, assuming the app isn't open to the public. You can also check or un-check "Show in User Picker" so you do not assign them to new records in your app.
However, if you would like to reactivate them, you can simply reassign their role and check "show in user picker." They will maintain all of the same access as before.
This might not work if you give access by groups (we don't use that feature, so I wouldn't know), but has worked well for our purposes. Hope this helps!
