Hey guys, I became a member here basically just to post this...
I don't think JPRA is under a long refurbishment right now. I was at the park yesterday - my first visit ever - and when I got to the lower lot, there were a bunch of people working in the splashdown pond. A few hours later they were gone and the water was being refilled. On the studio tour, I could see that the water in the upper part hadn't been drained. My hunch is that at least right now, this is a relatively short refurbishment.
As for why they have taken so long to do a proper refurbishment, remember that these parks draw people from all over the world, and those people want to get the chance to ride these rides. Jurassic Park was the ride I was perhaps the most interested in seeing. While I totally get that going during the offseason is risking missing seeing some rides, the longer a ride is closed, the longer that you disappoint people who are traveling. Disney World in particular has stopped most ride seasonal overlays because of the issues with closing them and disappointing people.
This isn't to say that the ride doesn't need it - I'm sure it does. But, I would have rather rode a half-working JPRA than no JPRA at all.
Because of this, Universal, especially with a super limited attraction selection, has to really balance things so that they don't have too many attractions closed, and that they can update them without crowds. It's not a matter of not caring for it, but figuring out how to care for it while not ending up with multiple attractions all down at the same time. With the exception of the Studio Tour, which they can swap in and out pieces of without taking down the full experience, when USH takes down a ride, they are taking down a huge chunk of the park. This makes scheduling nearly impossible to do.
USH is a pretty unique park overall, but it has difficult problems like this one because of it. While I'm disappointed I didn't get a chance to ride it, I was very happy with my experience overall.