If vet is toned down there is not need to preserve troops anymore. Suicide attacks become a basic strategy and its mostly about outproducing the opposition. It also means its possible to pump out T1 as long as desired and needed to then let them all die and replace them with new high tier units. No need to micro individual units to keep them alive. Wich would be more or less exactly as in most other RTS games.
Unit preservation matters a lot in other games. Warcraft 3 is perhaps the best example. Here, players expend high levels of effort to micro individual unit models to keep them alive, and invest in healing items and spells.
In CoH, people often send their squads on suicide-like assaults: as long as one soldier can make it out on retreat, you're happy. Actually, in CoH, the individual soldier matters less than in other games, as long as the squad stays alive.
In the end, reducing vet bonuses will not make unit preservation any less relevant in CoH. Again, I do not argue for removing vet. The vet bonuses would still be there, albeit on a more reasonable level, and reinforcing is still cheaper than replacing.
This is exactly ONE problem. With one faction and one specific unit.
If vet would be to strong in general it would be true for all factions T1 units. How many Vet3 Conscript, Rifle or Grenadier blobs dominate the game?
For most faction even doctrine, call in, elite infantry can't dominate on their own regardless if Vet3 or not.
Actually, rifles, grens and obers with LMGs also become ridiculous with vet, sniping infantry at long range. They are fine without vet. As I also mentioned, veterancy skews the medium vs. heavy tank efficiency too.