Why do (some) women not see the term milf as a compliment?

I dunno, man. having more than a single dimension of appreciation seems both exhausting and potentially confusing as to what you want from her/for her.
la donna e mobile.

Because when pronounced with all the syllables, “MILF” is not a flattering or seductive term. (Some) men think it is. It is in fact even less flattering to the man who says it.

It reduces both the man and the woman to occupants of a breeding farm. It says nothing about respect, affection, trust. Nothing about mutual support, emotional or financial.

In addition, it’s no secret that many men ONLY want the ‘f’ part, and to be perfectly honest, many men have not and do not bother to learn how to make that part mutually satisfying.

(Some) women do not see the suggestion or description in any way flattering or bolstering. We’ve known it for a very long time.

Perhaps because they generally do not like being objectified as a sex toy to begin with, and in addition are sensitive about aging (which treats most women worse than most men) as well as the term "mother" triggering a maternal morality role society has imprinted in most? Just guessing.

After my wife heard some college guys call her a MILF, I had to explain what it meant. Her reaction was, "That's good, I guess."

Because they think I’m old enough to be their mother when they might only be slightly more than 10 years younger than me.

Maybe because they are moms!!

because they don't understand acronyms

they probably saw American Pie

Does it rrally need spelling out?

Cuz pop out one kid and you're labeled for life!

You probably don't have a big enough D for the F part so they're only offended when you say it.

Because it is a p0rn0graphic terminology.