Your points above are all very relevant and realistic in the appraisal of the options.
This season has turned into a nightmare in terms of results and performances. We should have a potent enough attacking style given the players, but spend far too much time trying to contain the opposition rather than making them worry about us. That has to be a tactical choice. It's been an epic fail.
In general the message coming from the club is about the financial troubles and maintaining the status quo. The manager himself has repeatedly said his mandate is to maintain league status and develop youth to be sold. A solid enough business model but a negative and frankly uninspiring model for fans wanting to see a level of ambition and to be excited every week, so in that sense there exists opposite expectations between club (via manager) and supporters.
I genuinely don't dislike MM, he's an all right bloke and have no issue with him leaving in the past or previous teams.
My frustration comes from a team that are not progressing together, look unfit and uncommitted and look as if they are not sure what the should be doing. We are fragile and our tactics are obvious and ridged. That all falls on the managers shoulders.
More frustrating is that many fans now except the doings from Hearts and Aberdeen as readily as from Celtic, they have bought into the business plan and question why other fans are angry at the displays we are enduring. As you suggest we are an established team and many feel the club has set its bar too low in terms of ambition, here lies the debate.
I don't know the answer, I would like to see a manager in who has no fear and wants his players to be comited and fight every game. That doesn't mean I expect to win every game. The Scottish game isn't all that technical and a lot of times comes down to who tries hardest.
Our current manager is not getting any of that from the players.