The Blades counted assassins, thieves, and spies among their ranks. These weren't the guys you joined if you had a strict moral code.
There's the biggest failing of main quest writing in the game: being forced to join the Blades. I've always thought them buffoons, but they were much better executed in Morrowind and Daggerfall. As in, you could mostly ignore them. Joining the Blades implies that you care about the preservation of the Empire. That used to be their only motivation. Which is out of character for many peoples' characters.
I'd like to think that the Skyrim Blades are on purpose written the way they are: Lost, out of their time, and in search of meaning, desperately looking for an enemy they can fight successfully, and using the dragonborn as their weapon to lash out, since they themselves are full of bark, but no bite. Hell, the entirety of "The Blades" seems to be Delphine, who comes off as a survivalist hokerr, holed up in her basemant, fighting her personal war, and Esbern, who seems much more concerned about the past than the present.
Your final point was a thinly-veiled ad hominem attack. Let's drop it, shall we?
Alright. It seems we have rather different views on what makes the fundamentals of good storytelling, but there's probably no point in discussing that further...