You are ignorant. Please do not comment further. There are plenty of tanking mods available from commendation vendors and quest rewards. I have RE'd many of them, and never obtained a schematic. Even if I were successful, it would grant a purple version, there's no known way to get blue or green.
There is no indication that this is by design. It appears to be an oversight on Bioware's part, and I hope it is fixed soon.