Yeah, I don't like this idea. In no way will it open the game for more company diversity it will in fact limit the companies to just a few options per race.
The way I'm playing right now is changing my company after every match from a 9 companies builds I have with humans and this is in 250 AP, in 400 AP you have way more options for building company rotations, if you lower the limit of foot soldiers or archers the game will lose part of the core balance.
The zerg building is part of the intended Meta, if you limit the amount of foot soldiers or archers Undeads and Humans won't be able to compete with Wolfs (in my opinion). What we saw 4 or 5 weeks or so ago, were Wolf companies that could play the zerg Meta and they were king of the game, the devs changed them to their intended no-zerg way for a reason, if suddenly Humans and Undeads are forced to play the same very limited numbers of units as Wolfs then Wolfs will be king of the game again.
What I have been thinking for a while is how about a random set of rules in the pre-game window, you see your oppenent's name and race but also the game randomly (from a set of pre-tested scenarios) tells you the limit per unit (not lower than 2 for example) and a limit of units in total (total of 7 or 10 units for example) for the companies, or maybe something like no Casters or no Elites or no Ranged or no Legendaries, the numbers and the rules change randomly and force the players to have a set amount of units builds variations to changed to and build their new army accordingly to the opponent and the random game rules. There was another post suggesting a way to be able to save your companies, that system will work great with this idea.
I think this will be a lot of work for the devs, but could totaly pay off if it adds more variety to the way the game is played right now, there are so many units in this game already and so many combinations that im pretty sure not even 20% of the player base have ever try. As I see it, right now most people try a combination of units for a whole week and thats what they play all week, honestly that way of playing lost the fun for me long ago. If the devs implement my idea, the ranking won't show what company setup is the stronger for that week but the way it is suppose to be, what player is the best at playing the game.
I have been playing this game for 3 Months if not more and I'm sure I haven't play every company possible combination with all the races on all AP brackets.