Do you want Germany to raise military expenses?

[Seamus Fermanagh]

Retaining high quality specialists is important. Long service enlisted have traditionally been the backbone of successful militaries. And some skill sets are valuable on "civvy street" and it requires effort/compensation to keep persons with those skills in the military.

Fixed AA
AA defenses are a vital component, as long as they represent a significant threat if unsuppressed. A tech-savvy opponent can and will suppress most such as part of an effort to strike successfully from the air. Yet every multiple-millions-in-cost fighter/bomber that has to be tasked to suppress or destroy a targeting radar or missile site (and you can generally get a SAM battery with targeting radar for less than the cost of the fighter) is one fewer aircraft that can actually be used against the desired target. Even the use of stealth to spoof such systems and go for the target anyway still represents a significant expenditure to overcome the static defense (though admittedly with stealth tech, the cost may have been largely paid in advance).

Following the old Sov' mantra that the best defense against a tank was another (preferably more effective) tank, the best choice for air defense are active air forces that can interdict and destroy the opposition. This is NOT cheaply done however, so the fixed assets more than pay for themselves in altering the calculus of an airstrike.

Special Forces

This has become the "catch-all" term for two very different military functions: commando-style units (SAS, SEALS) and units serving as trainers/cadre for foreign troops (green beret).

The former are highly trained and very expensive light infantry. They add a value by using a quasi-guerilla approach in all conflicts. High value raids, covert recon, and other short-term high intensity missions are their specialty.
The latter are also highly trained, but a key element of their function is to serve as training/command cadre for a force of "locals" and as such they handle training, medical care, 'heart-and-minds' efforts and the like in order to ramp up the capability of the indigenous force so favored.

If these forces -- which almost always 'cream off' the highest caliber of service person -- grow too large then they hurt the larger military from which they are drawn by removing too many of the 'best and brightest' from leadership roles in normal units, watering down the effectiveness of the larger force.

Recruited sparingly they can, of course, generate a lot of value for the cost expended.

It should be noted that these same functions -- raiding and cadre -- have been handed to "line" units and these line units have often performed them quite effectively (US Marine Constabulary in Haiti).


Intelligence

SIGINT is hugely useful, but only if you can tap into the signal. Not all signals are broadcast.
HUMINT is much more expensive, and less likely to generate useful intelligence for the expenses borne. It can, at its best, get access to key information that is not broadcast.


Overall size of regular forces

Both size and quality are components of the deterrence value of a military. No matter how skilled, a superbly trained and equipped company of commandos cannot be in two or three places at once. If regular forces are too few or their capabilities too anemic, then an opponent can attack, knowing it will lose any engagement where confronted by the hyper-elite opposition, but knowing it can win the war despite losing all of those little battles since the overall coverage is too thin.