A possibility for 'who wants this' is the faculty themselves, right? There's been a steady increase in the number of people who actually have PhDs which might not be rising concomitantly with employment opportunities. More PhDs might lobby for universities to provide a greater diversity of courses, necessitating the creation of more employment opportunities for those PhDs. Since universities are subsidized and demand isn't a great limiting factor on their behavior, lobbying by PhDs might be effective. (It's possible to think of some reasons for this: administrators making decisions might want more PhDs either out of class solidarity -- if they have PhDs themselves or think of themselves as academics in some sense -- or out of a desire for power -- since more PhDs employed at the college might add to its prestige, or give you more people to 'rule' over in a certain sense. Administrators are probably more directly invested in growing the raw number of administrators, of course, but growing the number of faculty might be an effective way of justifying administrative growth.)
Adderall caused weight gain for me, and anecdotally also for a close friend of mine. Wellbutrin works, though, at least for me personally.
Lots of drugs have effects that vary wildly between different individuals (and they may even sometimes cause paradoxical effects), so I'm not sure that variance in response to amphetamines is necessarily that much of a hint about what is causing the obesity epidemic. If semaglutide works universally, or nearly so -- and early studies are very promising -- then that might be a strong hint as to what is causing the obesity epidemic.