Ever listen to Mitch Mitchell? Imagine getiing him in the studio, and realizing he wasn't playing time all that well. Then you go and Pro tools his parts and ruin his vibe.
Buddy miles speeds up like a bastard on the New years Filmore East record.
How's about some of the Dylan tracks where there's a train wreck in the middle somewhere.
How about the band that comes in, plays like they're on fire, but speeds up from the begining of the song to the end, quite unintentionally, then drops a beat on the middle 8, again, by accident? Do they suck? Are you going to "improve" that take by having them play it to a click track, then edit all the boo boos out?
In regards to singing out of tune, again, Dylan anyone? Who cares if he's out of tune? He sings with conviction. How's about Robert Plant? His tuning kinda sucked, but he sure made up for it by singing like the world was gonna end tomorrow. Pretty much anyone that was in the studio before the era of comping tracks like crazy and pitch correction would sing out of tune from time to time, and maybe all the time---hell, if it's a little flat, it could sound cool and bluesy.
SOme guys can't play perfectly in time, but they more than make up for it in their parts and their vibe.
Plus, the guy who made the comment about if you can't play in time, you shouldn't be in the studio sounds like a guy who works at a studio. So to him and anyone else working at a studio, if someone is paying you to record them , even if they can't play in tune or in time, then you gotta do the job they are paying you to do. And beleive me, I am sympathetic to all of you folks out there dealing with sucky bands. It's not nearly as fun as recording the good ones.