Joe,
I agree with you that 15 is the weakest on the course, but I disagree with your assessment of how the hole plays. As you note, the pins are blind from the tee, but not from the previous approach shot. So check them out and it should in large part solve your problem. As for the downhill put yes it is difficult to impossible, so dont ever hit it above the hole. But even if you do, you can almost always get your next one on the right level. The one exception might be if you are back left and the pin is front left, but from here you have overshot the pin by at least 20 yds, uphill and that is certianly not the architects fault.
My problems with 15 are twofold: First, the green is the only one on the course that feels a bit contrived and doesnt blend with the surrounding area. (That being said, it might be one of the better greens on the other modern courses in the area . . . a testament to the quality of the rest at RC and the weakness of its neighbors.)
Second, misses just a little left are often lost/unplayable in the brush. I'd like to see that side a little cleaner so one could at least try a difficult recovery. That being said, I dont think the hole plays too badly. It is a fun matchplay hole near the end because there are quite a few degrees of possible agressiveness depending on the circumstances.
As for 17, the right side is more difficult to hit but the left side is much more difficult to putt, so while sloppy shots left are not punished, I am not sure they are benefitted much either. I agree that this hole relies on a firm base for the hole to be most effective with any pin.
So then I'll second your nomination for No. 15 for weakest of the weak. Let's see if anyone wants to speak in opposition.