All valid points, specially even if you are having fun, if you have difficulty hearing your drums, the rest of the band is simply too loud, and you definitely need to wear hearing protection. ( And turn their volume down, there is no need to play at full volume during a rehearsal).
Professionalism is hard to attain because in most bands that are starting there is usually at least one if not more band members that just want to reap the benefits of being in a band (read groupies and booze), without putting the work. (singers are particularly bad at lending a hand for load unload, and definitely won't know anything about setting a PA, they just want to show up, drink and mingle).
Non musicians giving unsolicited advice.... That is probably never going away, but a rehearsal should be only the band (most of the time) I get that some band members want to invite their friends and it turns into a party but that should be the exception and not the norm.
Improvements in quality... If after a few sessions there is no noticeable improvement then you are wasting your time.