I know that the Haradim do not typicaly serve in Hesder, but even if the religious zionists are attacked then how are you going to encourage the Haradim? trying to force the Haradim will not benifit anyone. You have to make the IDF look like a place that they WANT to go (you get more flies with honey than viniger). A big part of that is the sexual imorality in the IDF as well as other issues. I honestly dont think that the IDF wants 40,000+ Haradim. They think they are more troble than they are worth and they fear them getting into higher millitary positions. Its better politicaly if the Haradim are used as scape goats and the Haradim dont care as long as they get $$$ for their yeshivas. I would bet you that if the IDF realy wanted to attract Yeshiva students it could.
from the article: Draft deferrals for yeshiva students surpass 50,000 mark in 2006