As much as I love DL, maybe you should consider those other things SoCal has to offer and hit up DL another time. I want to say the magical feeling of it all will overwhelm you and you'll forget your disappointment but that's just not a guarantee these days for all the reasons you've listed. If this is your one and only chance I would say go to DL but if you'll have other chances in the next few years the parks should be in better shape in the future. As for shows and park hours, in order to get more you have to visit during a busier season, they are only extended when there is a large amount of people anticipated to be in the parks. Not coming back to SoCal for a while? DL still has some wonderful things to offer you just won't encounter at WDW: Carsland, WOC, Matterhorn, park hopping so easy it can make a WDW vet's jaw drop, and even the next generation of monorail (I felt like I was stepping back in time when I rode WDW's monorail last year). Is it still fun? Yes. Is it still somewhat different from WDW? Yes. Will it be a better experience in the future? Yes.
Other things in Southern California you could do include the San Diego Zoo and the San Diego Safari Park. Both are very different experiences and I highly recommend them to anyone visiting SoCal! The Zoo is world class and you can barely see the whole thing in one full day, and the Safari Park is just so different from traditional zoos (there was a jaguar run when we were there (happens if the jaguar feels like it)- I swear it ran by so fast it was a blur of color). We did an amazing tour at the Safari Park where we drove INTO the giraffe and rhino exhibit and it was one of the neatest things I've done in my life. (Expensive, but an absolute steal when one considers the cost of going to Africa to try to do that!) There are other things to see and do in SoCal and so if part of you is overwhelmingly concerned about being disappointed in your first trip to DL put it off and explore what else we have to offer. It's ok!
