I can easily spend an entire week at the 2 Universal parks. We do it every year. We hit a park in the morning, have lunch, head back to Hard Rock for a swim and a nap, head to City Walk for dinner, then go to the other park for the night. We love it.
Hotel guest may very well make up many people at VB but I have no way of knowing the numbers.
I think the problem is VB needs more slides. They are working on everything else but it looks like everything else won't be enough to handle the crowd. More slides, they don't have to be great, just decent and high capacity. I think part of the problem is too many slides that can only handle a few people per minute. Example is the slides that are 3 or 4 people at a time, by their nature they can handle 3 or 4 times the amount of people per hour then a 1 person drop slide. Same with multiple race lane slides. It's true over at Disney as well. At Blizzard beach that one high drop slide has big lines on busy days. That doesn't annoy me because it's like the trophy slide at that park but they have plenty of other less thrilling higher capacity slides at BB.
From a company stand point, having too many people show up to your park isn't a bad thing. In fact it's a great thing and very profitable. Universal may be able to pay off VB in a year. That's not a bad thing because it encourages them to keep building. I don't know about Universal's plan for the W-n-W land. I think that may be the hotel rooms that push Universal into too many rooms. Too many rooms would probably mean a slow down in building at the parks etc.
In the end I hope Universal succeeds but VB needs more stuff at the moment.