As for varying opening times, I've never had an issue with it. I feel like it's a part of every theme park.. Some open later, some close earlier. Just check the guide and plan your day accordingly. Sometimes I wanna run to World Showcase at Epcot, but I just can't.

Not until 11am at least.
You make some good points, but when the park opens and you have several attractions at Universal Studios not open it kind of makes you wonder why they just don't open all the park at 11.
I suppose I am talking through my son's perspective really, he has autism/non verbal, the majority of the rides he enjoys don't open till at least 10 and often more like 11. I also get the feeling they open Barney 'any time they choose to', on that side of the park including Amity you only have MIB and The Simpsons open.
We suffer as our son is such an early riser, so getting to the parks early is always our plan. You also have to bear in mind the heat, we usually visit during the summer or Easter so it's nice to arrive at park opening when the crowds & heat are more suited to touring the parks.
Hence it's an ideal opportunity to get a couple of hours in on the rides he loves before the crowds build and before the temperatures rise...but you can't do that if the rides are closed.
Naturally with a disabled child our position is different, others have more options to vary their touring plans, for us that is more difficult - when your plan is ET, Curious George, Fievel's, Barney and Jaws it's a different picture....you can adapt for sure, go to IOA first instead perhaps...yeah we did that, and Popeye's wasn't open till 11, a couple of rides at Suess weren't open till 10.
Sure there are similarities at Disney, but on here that is irrelevant as we are talking about Universal.
As far as I am concerned all parks open at 9 all rides open at 9 too.
There are just the 3 of us, in the big picture of the 1000s who visit each year we are insignificant, we have enjoyed many good times over the years and been Annual Pass holders too, but just can't see us visiting US on our holiday next year. I just think that's a shame, especially as ALL the parks should be looking to cater for disabled guests more.
On leaving the park we even had to move the barriers *where the security bag checks are* because we couldn't get through to the car parks with Joshua's wheelchair.
