Why not make a low tech game option - if you ever played original total annhilation it was always fun to turn off level 2 labs. In this game it would be equivalent of turning off large or late game units, for example the game would not allow you to make:
Annihilator
DDM
Nuke
Missil silo
Strider lab (turn off morph from units like crab)
Behemoth
Superweapons (BB, starlight,Xeneth, disco etc)
No com morphs
This would limit people to make lab units - people opting to defend will be limited to weak defense like defenders, LLT, heavy laser and gauss cannons which would mean units can overwhelm them.