u/Double-Jump-Lover

Upgrading the base plants should also upgrade all that plants fusions. Making it so the player upgrades the entire plant family instead of just one plant will add a good form of progression that can allow Popcap to keep the upgrading for the profit in a way that doesn't hinder the gameplay, also the upgrades being expensive would be more justifiable because the player is upgrading an entire group of plants instead of just one.

While I do understand wanting to removing the upgrading entirely but I think the upgrade system in this game is actually pretty neat, gaining new abilities and having to collect a special currency for the important upgrades is a significantly better system than whatever PVZ2 has going on.