Yeah, I'm just not very convinced that the net gain of having Randall Cobb returning kicks is worth the net loss that would occur should he get injured on special teams. Just like we often hear about managing running backs carries to not wear them out over the course of the season, the same logic should apply to Randall Cobb, imo. Even if the logic of taking him off of special teams isn't to minimize injury opportunities (which is solid reasoning), simply limiting his touches is an important management decision for the coaching staff to consider. Cobb needs to be fresh and healthy late in the season, and special teams isn't going to help that. I think I would rather POTENTIALLY (but not definitely) lose a little explosion from my kick returner and maintain the explosion that Cobb provides on offense. Sure, keeping him as the returner doesn't necessarily mean he would lose any explosion on offense, but it's definitely not going to help. I feel as if someone such as J. Ross et al. could still provide a solid returner option so Cobb could focus on becoming a dominating offensive weapon. Cobb is going to help the Packers the most on offense anyway, so it would be tough to convince me that anything that potentially hinders his offensive contributions is worth it.
The exact same reasoning could be applied to Clay Mathews (or several other starters). I think it's safe to assume that CM3 would be a better special teams contributor than some of the young guys. However, it seems to be recognized that the added repetitions on his body isn't worth the perceived slight increase in special team production.
I do agree with the argument that if Cobb truly is SUBSTANTIALLY better than any other returner option (and I mean it isn't even remotely close), then it should be strongly considered. I would still probably choose to have him focus on offense though, simply because I think that's the way he contributes the most to the Green Bay Packers.