re: Poker & Why must the blinds be defended?
Basically what Arjonus said.
I think OP raises a good point in asking why the MP shouldn't ''defend'' the dead money.
The game of poker itself is based upon the existence of this dead money. I recall a line from a book that if there were no mandatory blinds, the correct play in hold'em would be to fold every hand except AA. If you fold you lose nothing and there is nothing for you to win by playing a weak hand, playing even KK is a mistake if everyone plays optimally ie doesn't play any hand that isn't AA.
To emphasize abit on what Arjonus said, it is true that a lot of players would lose less by simply defending less. This is in line with TAG or even NIT playstyle being recommended for new players because your hands are strong and you don't face too many tough decisions. Defending the blinds more puts you in a lot of marginal spots and for inexperienced players, playing these marginal spots, especially out of position will just lose more money in the long run than just giving up the blind.
BUT that said, as the games get tougher, if you keep giving up a lot of blinds, lets say you only defend 20%, you are -80bb/100 from the big blind not considering the times you do defend. It will also be extremely easy to play against your blinds because of your tight range and you being oop, so you will likely not be winning much when you do defend, this will badly hurt your winrate in tougher games.
That said, most players at microstakes are not capable of taking advantage of this. I do think it is good to learn blind vs button situations even at micros, maybe especially at micros, because most players have no idea how to play these spots and you can increase your winrate by alot knowing how to exploit them properly. BUT, if you can't play the more standard TAG spots well enough yet, imo it will be too much to try to learn how to defend blinds in the much much more tougher marginal spots where variance will also be higher(due to nature of being marginal).