It is a real concern for those of us with 'slight' mobility impairments, not bad enough for an ECV but bad enough to 'make every step count'. I have also wondered what, if any, accommodation they make for people like me. I suppose they'd tell me to rent an ECV, but then that would take one out of service for someone who really needs it. Plus, rental fees are income, albeit a small one, and running the trams is an expense, probably a very large one.
There were no trams when we were at WDW, either, but we got there for rope drop so got 'close enough' to the turnstile. That's not an option at M&F. As far as TS, as someone who goes solo these days, after dark I just feel safer at M&F as opposed to the spread out TS lot.
Bluntly, Disney doesn't care. They really don't. Someone looked at the cost vs the bad PR, then looked at their park-going public and said "Meh, let 'em walk or rent something to get around in. They'll put up with it and not raise too much of a stink". And unfortunately, they're right. We aren't raising a huge stink. We're quietly seething, emailing GS, posting threads on boards, maybe a few are 'boycotting' but that's about it.
I do think they'll be back at some point in the dim and distant future, but it would take a HUGE boycott or, more likely, several highly publicized incidents involving guests like medical emergencies, personal crimes, or injury lawsuits to get them to step up bringing the trams back any time soon.