Ive thought about this myself, and even made a half-arsed mod of it. Primarily it focused around defensive area of effect artillery and long range emps. The only way to get your assault units close to the enemy defensive artillery was to paralyze them.
It also had some other interesting things though. One was an Impulse wepaon that can repel enemy units, or using a mountain as a ramp, repel your own units toward the enemy (Which is quite fun but not often practical).
The other was a digger, which could make trenches, obstacles, and cover. At a pinch it could even bury another unit down a hole. You can do this to an enemy as a sort of conditional paralyze (He is stuck down there until you can get a unit which can Restore ground to dig him out). Of course if the hole was deep enough nobody can shoot over its edges (Or in some cases, it puts that unit under water, which makes it prettymuch impossible to hit). Thus, you can bury your own buildings and units as a defensive measure.
Ive dabbled with the idea of making modular units, too (Probably using transports). So you can mix a chasis with one set of abilities, with a turret with others.
For example, a chassis that has a deflector shield (That effects your own units fire, can you do that? I havent checked yet) could be mixed with a turret that has a plasma weapon. The plasma weapon would, of course, be repelled outwards at tremendous speeds by the deflector shield (But become loses prettymuch all accuracy as a result).
But perhaps these ideas are not exactly what you had in mind.
I think a mod based on micro management of a small force is certainly worth making. Most RTS's have variants where you are given a small fixed force with which to fight, and they have a lot less potential than Spring does for interesting micromanagement (Like line of sight, ballistics, tracking, firing angles and things other RTS's just dont have).
