Your suggestion shows a complete lack of understanding of the game. Returns don't generate SP advantage. They enforce a low unit-count, low-SP environment where agility focusing down on a smaller number of units can close units before they get a chance to act.
The downside of this is that most of Falkow's units have their attributes biased towards agility and away from vitality, and in some cases (Elite Fencer, Emana), not even having the regular amount of attributes as a level 3 because the balance team is comprised of bad players who are biased against Falkow and hate agility manipulation that can be done over and over.
The way to smash face is to
A) have units that don't cost SP to revive, thereby negating returns' ability to deprive you of SP by taking advantage of temporary field position advantage.
B) have units that can close and keep going (Dilate, Broken Virus, EX Cak, lycans)
C) have one high-defense unit that can take a hit from a couple of units and live (Grebados SS!)
D) Have units that are higher level than can be returned.
Now, to stay on topic, I have a different vision for return mechanics:
I want to point to a card called heartbreak. 3 SP to cem a level 5 or lower closed unit. Except this has been powercreeped out the wazoo by bitter destiny. So, I say this:
Change return to this:
Open: Return level 3: return target enemy unit of level 3 or lower.
Open: Return level 3 fails: return target closed unit to its owner's file.
Open: you cannot set a grimoire for the next two turns.
In other words, if WK is up against a bigs file, suddenly the returns aren't completely dead weight in the file.