Problem:
Buttons can currently be clicked by anyone that has view access to the record. If a button click leads to records being edited, then anyone who has view access to the record can cause edits. This is obviously not great.
Solution:
Allowing access to the current logged in user in formulas will allow us to customise button URLs depending on who is logged in. This could mean deactivating a button when the logged in user is not one of a select few. Undoubtably there are other use cases too.
Allowing access to teams in formulas (either as a property of the user or as standalone lists of users) too would work great with this. We could allow an important button to be clicked only if someone is a member of the Management team.