When we drafted James, Ginn wasn't signed, Williams was just coming off the 2 fumbles against the Giants, and I do not think Gore had signed his extension yet. So at the time it looked like we had a need in those areas... but time has shown Gore is signed and healthy, Williams is looking better than ever, Ginn was resigned and looking good. This year has shown we have young and athletic guys already in those roles and we may not need James for another few years. And RB lose their value quickly as they get older. So it doesn't make any sense to sit a RB for a few years like it does a QB.
When Kapernick was drafted 2 years ago, the wildcat formation was the craze of the NFL. Smith hadn't signed his extension. Smith was coming off of a bad season. Since that time, Smith is the second winningest QB (last season and this season). Smith is still young for a quarterback, so very like to have 5 or 6 seasons left. So you do not just replace him with Kapernick unless he has shown himself to be better, and I just don't see that happening. So keeping him as our backup for the next 5 or 6 years does not make any sense.
Completely understand players need to sit sometimes. That is why I didn't include our first round WR in this list. He is going to be good, he just needs time to learn, and Crabtree is the only entrenched player infront of him. And I understand we need depth... but already have lots of quality depth at RB and I really like our 3rd string QB. I think his accurate passing and cerebral play make him a more idea backup because we would not have to change the game plan.
Again, not a knock on Kapernick at all, but I do not think we need him because of Smith's transformation at the QB position.