I've been saying for a while that, the less "important" player we use for returning kicks and punts, the better. Now, that's not to say I think Franks isn't important. I've gone on record plenty of times and said I like what Franks has shown when he's been on the field, HOWEVER he'll be getting significantly fewer snaps than HD, and if the loss is minimal, we don't need to be trotting HD out there. Might sound mean, but that's the nature of the business. You wouldn't want Brent Grimes returning kicks unless we had nobody else to do it, since an injury to him would be way more devastating.
If I'm not mistaken, Franks did some punt returning last year and had some very positive results. Why the coaching staff didn't consider him first is beyond me, but I guess this is why I don't get paid to make those decisions.
It's not a knock on Franks, his 45 yard return last night was excellent, and he showed great vision of using his blockers to the fullest effect. If he continues to return kicks like that, I can't see him being looked over for anyone else if only because he's the best option. However, the coaching staff also needs to consider which option is safest for the long-term health of the team.