I dont think, just because a less powerful cartridge is sufficient for deer hunting , it makes the mighty 7mag a bad deer round. I dont see how a deer can be too damaged or "too dead"
I think what you hit, like bone, muscle , or just skin and organs is gonna have more of an affect on "meat damage" Than what you hit it with.
The 1st deer I ever shot, a fawn,was w/ a 30 06, 180 gr. corlock . Way overkill, but my 1st shot was at 10 yds through the ribs, "penciled through" but dropped it, I put another(same load) in its neck as it layed kicking in front of me and the hole was litterally big enough to put my fist through!
I think the 7mag is a great round for whitetails any all ranges w/ 140grainers, as long as its comfortable for the shooter, I say thump away.
