I mean, that's just the natural consequence of x-com metagame. No matter how many different types of soldiers a mod has, there are only two actual roles they can fill - chumps drawing reaction fire, and snipers killing stuff. Ogres are the best chumps thanks to their hp/armor/psi stats, so you end up filling half your squad with them. If you nerf ogres, it will be high HP freaks instead.
No matter what you do with balance, there will never be a valid reason to run "a little bit of each". You pick the best chump type, and the best sniper type, and run exclusively those.