I see what your saying, but i dont think there is anyway around that. It's a class mechanic. We have moves we can do out of cover, but if you really want to get down to business and lay down some serious dps you have to get into cover.
Its like complaining a stealth class has to go into stealth before they use an stealth-only move.
Personally, i played a druid through most of my WoW experience, so it took almost no adjusting for me to enter into my stationary cat-form to dps.
There is a way around that, the original poster gave the answer - for which I wholeheartedly agree.
Also, even though it has been three years for me since I played WoW, I think I still remember you didnt need to leave cat form first to cast NS+HT.