Definitely agree with adding Zombatar.
There already is a "hard" mode, when watching the credits you can enable a "harder" option, which will make plants shoot slightly less faster and make zombies slightly more resistant from what I understand.
The level editor is a good idea, but I feel like before adding new features, the issues (in the game) that are currently known, and missing features have to be fixed first, basically what I'm saying, the game should be fixed and work how it should, before adding new features (in my opinion).
