Seriously it's the cap or you are fooling yourself with no proof to back it up.
SE said before FFXIV launched that the cap will be 50 at first.
the dats contain skills up to lvl 100, wether they will be used in the future or not is up to SE.
if you're so pissed about MRD only getting bloodbath II at 50 then i suggest you to play LNC next.
LNC gets different weapon skills, sadly most of them sharing the exactly same animation, so don't complain =P