rear deck/sweep/layback
You don’t need to lay back to do an effective sweep roll. The sweep method shown in “the kayak Roll”, which emphasizes torso rotation over angle, does not require the paddler to lean aft of the cockpit.
That said, I’ll always prefer a low rear deck to a tall one. It just gives you more options.
Didn’t “need” to but -
That didn’t stop me from taking all the real estate I could at times. The point was that I couldn’t do it right yet, so a little extra running room could make the diff between getting up or doing a da-whup. Having a lower back deck gives you more time to at least fight your way up and scare a few more fishes when your roll technique isn’t all there yet, regardless of the exact roll you started out trying to do.