Maybe they are trying to fix their mistakes. If done right, revamping could be great. I have always thought, we should have new mobs and bosses in old instanced content. So if you want to run Dead Mines at level 120, it is not Vanessa Van Cleef. Or that if you wanted to run it at level 20, it was still her father. So several different versions based on level. That progresses a story and keeps content relevant. Outland could be done so the results of our actions during Burning Crusade are shown. New bosses and thugs throughout the land. Etc… So if you go back at a higher level, you’re not doing the same things. Other minor things could also occur like rebuilding the Loch Modan dam. Fixing the flooding in Menethil Harbor. Even villages that grow and get larger. This creates a breathing and progressive world.
Ideally, they should restore the old pre-cataclysm world. At level 80, your character goes through the cataclysm and things change and you experience the new world. This is how phasing should have been done. It was what I thought would be done when they announced it with Cataclysm.
Parties should always be in the phase of the party leader so you can play with friends. There would be a lot of work to get it right after so many years of getting it wrong. This was the biggest failure of phasing and it continues into BFA.
There is just no faith in the current developers to do this. They don’t work to make it the highest quality they can. They are working to meet budgets with the barest minimum of work on an old game.
Boosting solves another issue altogether though. It is to combat the idea of leveling after returning to the game. If you left in Mists of Pandaria and returned in BFA, you wouldn’t be able to play with your friends. They are all level 110 or higher. You’re 85-90. Providing a boost allows you to play with your friends. It also allows a player to bring in a new friend and have them be at the max level range within seconds. If people want to go back, they can create new characters to experience the old content. That I believe is the idea behind the boosts.