Well it is quite simple. Star Trek Online is a product. It was designed to make money not to realize your wishes.
The fact (and DanStahl often said so) is: Klingons are just a bonus. You cannot make money with them. So the designers create more Fed stuff, cause the majority wants these products and are willing to spent money for them.
Look around. Maybe 10-15% of the users have a Klingon character. The other gamers use only Federation characters. Star Trek is about the Federation, NOT the Klingons!!! The Klingons were creates as their enemies, ölater they became their allies but they were never mentioned to be more than that.
I am all for making some of the clothing options faction neutral. Section 31 would work great over on the Klingon side, and definitally the Merc pack options. I actually thought they were Klingon usable when I bought them. What is really stupid is my Klingon Joined Trill can't even wear the Merc pack. How annoying is that?