One thing I am trying to do is create a true campaign feel. Right now no matter how many 'mechs or vehicles I destroy there are always more. I am currently on an objective raid, and have destroyed a company of 'mechs, and probably 2 of vehicles, and yet the only result has been to reduce the operational tempo. I have been on planet for over 3 months for a raid that should have taken only days, weeks at most and am no closer to my objective.
The campaign scenarios I'm setting up are designed to move towards an objective. As the player moves forward, successfully completing missions and destroying enemy units, the enemy gets weaker. This would also allow certain events, such as enemy or allied reinforcements to actually mean something, as they would actually receive reinforcements. Along the way I am creating side missions that can further assist the attacker, such as destroying the enemy airfield. This will prevent the enemy from using air assets during defensive missions for the next 3d6 weeks (The defender can still used them offensively, they would just launch from further away and coordinate their timing with the rest of the attacking force, defensively their would not be time to get to the battle before it's over).
I am currently (by hand) creating OpFor and allied TO&Es. These allies and OpFors don't use maintenance, repairs, healing, parts or money. Basically, if an OpFor 'mech was destroyed it's removed from the TO&E, otherwise it is instantly and completely repaired.
So, what I would really like to see, is the scenario generator to choose, rather than from a RAT, from my OpFors or allies TO&E. This could be by .mul or straight from a campaign file. Either way it would choose only 'mechs and other units that that force currently has in it's TO&E.