Those who are in the government represent people who believe that Israel survives because they are praying, which is much more important than serving in the army.
The waiting for the Messiach thing, is more in the
Neturei Karta territory. these are the ultra orthodox guys you see in anti Israel protests, Iran's holocaust denial conference etc'. they'll team up with anyone who is against Israel, not because they care about them, but because they want Israel gone for their own religious reasons.
As for the topic at hand, it's not that simple. do you really want tens of thousends of trained soldiers, which will be more loyal to their rabbis, than to the state? it's already a minor problem with religious soldiers who do serve in the army, but get conflicting messages from their rabbis.
National service is a different issue. i certainly support having those who do not serve in the army, serve instead as a free labour force and it also might help them to integrate better with the rest of the society and perheps learn a profession. however, the problem starts much earlier own, with the ultra orthodox education system and trying to change it, is a much bigger hornets nest.