I know that LUNA SEA are popular in Japan as well but in a certain crowd. They usually fill Tokyo dome (65,000 people) out of 126,000,000 in Japan. It's really not that much, of course they are BIG but then again look at glay or b'z for example. All I'm saying is that I honestly believe that Ryuichi makes more money (right now) on his solo career than by LUNA SEA, same goes for J.
Also, it's not fair with a statement. Most people want to push their limits, try new things and grow as a person, same goes for a musician. If Ryuichi sang with the same hardrock vocals he did in his teens, he wouldn't have a chance to grow as a vocalist. How would you feel being stuck at the same job, doing the same things every day without any promotion or a chance to try new things from 1986-2013. I think it's basically the same thing. So yeah, I too, as you, actually prefer his old vocals (my main obsession of LUNA SEA is pre-MOTHER), but I still appreciate his new singing style; which btw isn't actually new since he's been singing like this since 1997~.
EDIT: Also, what you may seem as uninspiring and overproduced crap is pure gold for someone else. Obviously a lot of people like his solo-era and I think most people who hates on him are stubborn fans who are stuck in the 90's.