I would caution against using collective words when describing your opinion. I'm sure there are some who share your view, but also some who share mine (and Billy's) - I would very much like to see Coach cards present, moreso than I would offensive linemen (and that's not a knock against the boys in the trenches), and I certainly wouldn't call them "specials" (I assume that's another word for inserts?). Pro Set worked them into the base set, and they were a nice bookend for team sets, which included offensive linemen. Of course, those were nearly 800 card sets.
2020 Donruss, on the other hand, has a 350 card base set. Take away the way too many 100 rookies, and you're left with 250 veterans. If Panini wanted to, they could easily cut the rookies in half to 50, and have two offensive linemen and a coach per team, with a few left over, and there would be a 400 card base set - which it is when you count the 50 SPs in the base set too. Heck, if they really wanted to, they could keep the 100 rookies, add more offensive linemen, and heaven forbid have a 500 card set.
Ultimately, you could (and should) have both. Coach cards wouldn't have to take the place of anything if the sets were large enough to handle a comprehensive checklist. Card companies just don't want to include anyone who isn't a recognizable name in fear of not capturing the casual fan (my opinion; no data to back that up), with the apparent exception of rookies in an effort to capture the investment side of the hobby too, I suppose. But Coaches are just an integral part of the team as any player on the field, and should get the same consideration as any player would.
I'll never quit collecting entirely, but I am downsizing. Check out my COMC store and help me thin out what I don't want so I can buy cards that I do want. See something you like? Send me a message on here, and we can knock the price down quite a bit. I'll even take a bit of a loss if it means getting you a card you really want.
