I think it's fine for GRs to be the go-to place for paragon farming, somewhere has to be. But it gives so much more that doing anything else feels like a complete waste of time if paragons are one of your goals.
People who want to play efficiently never run bounties and only run rifts to get keys.
If XP was buffed outside of greater rifts players who enjoy that content wouldn't feel so far behind and the XP farmers wouldn't feel as bad doing non-GR stuff.
This also wouldn't "buff" botters or gold farmers or anything since they can run GRs just as well.