I define "Mother, may I" as an extreme only of rule zero: in most games i am very happy to let the dungeon master have the final word, but I have been in ridiculous games where the dungeon master caused my character to be killed because I called the NPC a hobbit instead of a halfling.
This is the issue.
I agree that this was a terrible experience (a "ridiculous game"). But this is the crux of the problem with the term. At it's core, everyone agrees in the tautology that Bad GMs are Bad GMs.
Just like if I came up with some clever term, say, "One Ball, 11 Quarterbacks," or "Lowest Common Denominator Play," to describe unruly players who try to dominate the game by inventing fiction or rules lawyering, I would be doing nothing more than employing the tautology that ... wait for it ... Bad Players are Bad Players.
The trouble, of course, is that there is a group of people that chose to use "Mother May I" as a way to describe ... not Bad GMing, but an entire way of playing. A playstyle. In the same way that I might call certain games, "Lowest Common Denominator." And then turn around and say, "Hey there, I'm not being negative- just describing it! Don't take offense at the terms I use! After all, some other person also used them, so it's okay. Suck it up, buttercup!"
There is a simple way to get to the heart of the issue- go and ask people who play a certain style* if they describe their games in that way. If they (absent a failure point- like Bad DMing) would describe the way they play as "Mother My I."
Now, if they don't ... maybe you shouldn't use that term to describe them? That's basic courtesy. If you want to have an actual conversation with people (as opposed to trumpet your own preferred playing style), it's usually best to not try and rubbish the other side with loaded terms.
Then again, if your purpose is not to have that conversation, then don't bother. The choice is yours.
*In order to head off the inevitable, it has to be their preferred and most common playstyle. Not, "I used to play Mother May I, but now I know better!" Or, "Sure, sometimes I have to play Mother May I, but that's only because the sheeple don't play the games I like."