I understand the points you make about 'challenging' but the truth is if that keeps being used as an excuse, we will never get the 'depth of squad' (actually what does that mean?) we need!
Its not OK (at least for me) if we put out a lesser team and lose, sorry not acceptable... one of Fergie's standard replies to unacceptable defeats when he had made 8 or 9 changes to a winning team in one move, was "I always put out a team I think can win', true or not, it was not acceptable then and its not now!
Injuries are obviously a reason for changes, again some rotation of 1 or 2 is acceptable, especially with heavy midweek commitments, but not 4 or 5 or more players at one go!
Sorry I'm 'old school'