Questing has -always- been faster than dungeon grinding. Even with a pre-made group and “pumping”. A good quester with an addon will win every time. But dungeon grinding is a lot easier and less stress, less moving from random objective to random objective. Its a trade off.
Dungeon grinding doesn’t need to be worth any more experience than it is currently. If you want to go faster, go pump quests. If you prefer slow and steady, RDF it up. But no one should be saying things like “they should give comparable experience.” There’s always a tradeoff.