RE: healers - There are plenty of people who enjoy being healers, few that enjoy games where being healer is the majority of what they do/actively competes with them doing other things. If I wanted to armchair shrink the thing, I'd say it's because healing just places their ally in the same position as they were 5 seconds ago before they got hurt, which feels less impactful or rewarding than direct attacking or support effects which actively move your allies into a more advantageous position (going from normal mode to win-condition mode instead of them going from unhurt to hurt to unhurt again). All of this does differ based on how often your party members get knocked down/would be if not for you (do you feel like a hit-point battery or like the guy keeping the soldiers on the line?).
Re: clerics and wizards: -- I get the idea behind the notion that wizards get more utility. Historically, wizards got most of the dungeon-crawler utility spells like comprehend languages, featherfall/spiderclimb/fly, knock, invisibility/see invisibility, and passwall. Clerics got (more of the) negative status removal effects (again, the boring 'return to what you were pre-injury' spells), silence, shape earth, and late-game fly-alike (airwalk); plus everyone got tongues, plane shift and energy protection spells of some kinds. Exactly how much that resonates today likely has to do with whether those spells still dominate in your chosen playstyle, and whether status-effect removal feels like being the rest of the party's 'okayness battery.'
The one thing the videos included with this made clear to me is that no, not everything they are throwing out there as all-but-certain. If they threw out inspirations on 20 in one UA, then inspirations on 1 in the next before they tabulated results for the first, then they are genuinely experimenting and testing the waters on all this. Voice your preference. If the new Prayer of Healing doesn't hit 70-90%, or even if it does but in the meantime they experiment with a shorter Short Rest and that scores even higher, then they very well might scrap this in favor of something close to what you want.