Don't take aircraft <= so it limits the tactical options available...
Don't take spacecraft <= same there
Garrison two big shooty formations on OW on your forward objectives but only use the OW in life or death situations, that way they disrupt the enemy's plans without even activating <= that is only a wait option, without a direct possibility to do so. How is it infinitely better?
Most of the other are good advice indeed, but these tips would work against the opponent wether he outactivates you or not.
So it looks like you are advocating playing better against someone outactivating you

Anyway, it is not like small formations would lose their appeal. There are many other factors that make them better than big ones:
-Less juicy target means the ennemy will not always waste a big unit firing at them.
-They can control more ground
-The ennemy still needs one unit to place a BM on each of your small units, instead of just one on a big one
-You have higher variance on activation
-you can make better use of cover, and have less LOS problem than with biger units
-small units get a much better benefit from marshall orders
The bigger units would benefit from a higher resilience, and faster strikes, which is good indeed, but in no way is it a no brainer over smaller units, even without the outactivation benefit.
I don't think this has much to do with the fact that maneuver is more important in Epic than it is in WH40K. Most of it comes from relative unit speed and range: most unit can get further with a double that they can shoot, and assault is the preferred way to fight for most armies (maybe except the guard).
That and killing can only get you so far when victory is decided by controlling objectives.
The current activation mechanism doesn't make maneuver any more important, it only makes some army compositions less viable than other.
Allowing to pass turn is maybe not critical, but it will certainly not turn the game into a SM2nd edition sluggfest.