That's 20 more cost for LT, 30~40 more for AFV/APC and pretty much no change for other heavier vehicles. Also hey, that's net cost-down for Absorbant/Regen/Reactive. Walls would be useless, what? It's not like you have dual Ranged researched in the beginning, walls will still have their tactical usefulness. If you can get 2 heavy tanks to fire at the same piece of wall, it deserves to be punched down immediately.