I'd like to say the below is based on what I've seen and heard about the two lands and that my opinion may change after visiting, that being said..
In reply to Robert.W - If you are comparing Hogsmede to to this I get your point but not with Diagon.
The whole concept of Pandora is you are being invited to a completely fictional place which immediately makes the area less immersive in my opinion. Pandora seems to go out of its way to remind you that you're visiting this world which to me just reminds me it's not real, instead of actually making you feel part of the world itself. Diagon uses every opertunity to ensure you are part of the world with all the interactive elements and staff being in character. If that's not immersion I don't know what is
To me it's pretty clear Disney knew they couldn't immerse you like Universal can with potter, so they rolled with the "pretty" route.
I will personally enjoy both for their merits, I know which I'll like more but I will still love the other. They're both trying to do different things at the end of the day!