I can fully understand not being able to purchase a ship through the store (to have the ability to use it) unless you are currently playing a certain faction for which that ship is used for.
Example: Im currently Capt on KDF side, but I cannot purchase the Brel or any other high end T-5 ship till I reach Lt. Gen. Granted i cannot use them till I hit T-5, so why not allow me to purchase them ahead of time? It makes it less likely that when you have X% off sales that I would be able to get the ship at a discount.
Even when your not having a sale it would be nice to purchase the ability to have the ship for when I hit T-5. Since i can't use it till then anyway, whats the difference? Just like the Nebula, its unlocked for use, but i have to go to the ship yard to get it through the ship vendor as long as im the appropriate rank to do so.
So why restrict purchase of the ability to have it later?
Note: I probably already know the answer to this, yet Ive spent more on the C-Store items than I have for the game itself. So Im curious.........