>Are there reasons not to use this rough surface for the interior
>or exterior of the hive?
 
I don't think the bees give a brass razzoo about the quality of the timber.
 
They happily build nests in hollow trees, wall cavities, compost bins, old
fridges etc. etc.  Many of these places would certainly not have a smooth,
even surface on the inside.
 
However you build it, it must keep out the wind and moisture.  If the
material is good enough to last more than one season, so much the better.
 
Regards
 
Chris Allen