I thought that 7.5 allowed any user (who was part of the team) to change profile? At least, it does on my demo system!
I seem to recall you had to code that change.
Could be wrong on that.
I think this is a change of 7.5.1 to get Field Level Security, and - by its nature - this field too.
Are you saying you see the reverse - no-one can change this field ? Are you sure you are looking at account and not contact ?