As for the quality of Robinson Ranch, not sure what you think the rating and slope are supposed to tell me, but I've played the Valley course multiple times (a few times in over 5 hours) and it is not my cup of tea. As for the price, weekend rack rate at Robinson Ranch is $117. Not quite twice as much as Rustic ($66), but close. If the prices were reversed, I'd still play Rustic over RR. In fact, if the Robinson Ranch courses were free, I'd still pay to play Rustic every time.
I'm glad you enjoy Robinson Ranch, though. If more people were like you, then Rustic wouldn't be so damn crowded and the pace during busy times might improve. If you want to give Rustic another try, I'd suggest early morning or late in the day, You might find your 3-5 round sample size isn't entirely representative.