Is it me or are they all built the wrong way around? A castle staircase is suppose to favour the defender: shield agaisnt the inside wall giving the defender room to swing his sword around while the attacker is limited in how much room they have to move their weapon etc

In Skyrim, its all back to front :S

This could be considered picky.

In the real world of earth, yes.

In the fantasy world, you have magicka. Fireballs don't care which hand your sword is in

But the real answer probably is: the developers didn't know jack squat about actual fortification design and defending tactics in the middle ages. No murder holes, no nothing. We have crennelations, but they are hardly effective, and the walls of the castles are much too thin. Wells are indefensible. No grain stores in castles. No stocks of arrows. Bows are stored strung. Meh. It's a game