We originally made this product because of some friends overseas.  They were using extremely short AR's and wanted vertical grips but had nowhere to mount them.  

All of their short rifles still had standard front sight gas blocks with bayonet mounts (and of course, a bayonet on a 7" AR would be... a Joe Pesci thing!).  We thought it would make a great place for a picatinny rail, since we don't "affix bayonets!" much.