I've not yet come to understand why Sentinels don't wish to actually be juggernauts with large calibre weapons that can lock down infantry and vehicles from a range while being able to put down suppressive fire on tough to crack emplacements.

Think mid way between Alex's HMG and a Mass Driver. Slower firing, much more powerful auto-cannon rounds, get in position and you are like a Mini Turret but up close you are subject to faster moving dropsuits like scouts and assaults.

Incorrect. Because area denial roles require mobility. Heavies don't have that. The idea of a heavy being outside but being dangerous at range doesn't work because the heavy can't move around the battle field and change their area of denial. All they do is become open area campers and can't really commit to the battle very often as, when said battle moves or changes, that heavy won't catch up to the next fight till it is already over. Heavies will earn virtually no WP. Basically, they will be the closer range, slower moving version of a redline sniper.

That's the reason why people who play a lot of Sent don't want to do this. Mobility is the single most important factor in long range battles -- and since Sents don't have it they won't be able to do it.

Heavies out of CQC is a ludicrous idea. Change map design so that more points are open with no cover. That would right there solve your problem with no changes needed.

Breakin is right about one thing though -- this won't kick heavies out of CQC at all. It might reduce the number of them though.