The main problem with the Quest 1's (and Quest 2's) weight is that it's all in the front, making you feel top-heavy; you can actually make it feel "lighter" by adding weights to the back (commonly, external battery packs, but I literally strapped a ziplock bag of sand to the back and even that was an improvement)

The Quest Pro is a major improvement in this regard; despite being heavier on paper, it feels much lighter because of the weight distribution.

That said, I wouldn't be surprised if the waist-mounted battery pack is purely for auxiliary power for extended use, which makes sense.