I think it really depends on people. Even back in the golden days when Disney offered free dining, DME, paper fastpass, free parking at hotels, free package delivery, free dinner reservations (no $10pp penalty for no show), less crowded hotels, etc, etc, there were people who stayed offsite. And the offsite hotels aren't always cheaper either; Four Seasons is often more expensive than GF. People stay offsite because they prefer their offsite hotel for whatever reason.
For me, Disney hotels are always better. One big reason: I suck at driving and avoid it at all costs on vacation. Another big reason: I love Disney transportation. I get car sick easily, but not on Disney transportation, for some reason. So being on buses, boats, etc are themselves a fun ride for me that an uber ride just doesn't cut it, even though it's faster and more comfortable. I also like the feeling of "no cost"!
And then, the Disney decorations in the hotels (including the ones that aren't Disney specifically, such as the giant bowling pins at Pop) speak to my heart. It's just awesome every time I see it. The same is true with other Disney hotels. It may or may not be more expensive than offsite (though it mostly is), but it's superior from the inside out. I mean, the air itself is sweeter in a Disney World hotel. I'm not kidding.
And then, you can trust Disney more. For example, at the Universal Cabana Bay hotel, the reviews for the past month has been reporting that guests have to wait in line 4 hours to check in, due to lack of staff. Yes, FOUR HOURS just for check in! That does not happen in Disney. Why, you just go straight to your room with your magical magic band, something no other hotel possesses.
AKL is beautiful and peaceful. There's something magically African about it that I doubt you can find a hotel in Africa that's as good, where you can look out your 4 star hotel balcony at exotic animals walking around. (Plus it's much cheaper and easier to stay at AKL than go to Africa).
For me, every moment I'm in an offsite hotel, I feel like I'm missing out on something. But not everyone feels that way. Some prefer the Four Seasons to GF because FS is a 5 star hotel whereas GF is only 4.5. I totally get that. But for me, I will always choose GF over FS. In fact, for the same money, I will always choose Pop over Four Seasons. I can't help it, Pop (or any other Disney hotel) feels more magical, and magical is more important to me than fancy.
All the stuff Disney has taken away, such as the DME, are superficial, and mostly has to do with money rather than the intrinsic attractiveness of WDW. Like makeup on a beautiful girl. Makeup helps, sure, but she can look stunning without it.
Postscript: I will never stay at the Star Wars hotel for 3K/night. Not even if I win the lottery. That's just too weird.