I believe Andrew took away upgrades and made all Hospitals bought the highest level of upgrade from beforehand. Pretty sure, anyway... Upgrades were too hard to do, or not enough people bought them. Don't they already do 3+ hearts or so every few seconds? That already seems like a lot.
Yeah, many people boost now using there hospitals, and I think increasing it will just make everyone boosting their Mcmmo skills in their own town, no for this. Unless it has already been done, that I don't know about. It's also fast enough, I think that's enough, why do we need more?
It is plenty fast enough and more than enough health. Spend 10-20 seconds in there and you are full. Really, are you impatient..? I don't think that time will really make much a difference while playing...