User blog comment:Zombotanist/PvZ 2 Balance Tweaks/@comment-24735666-20160425180257/@comment-25982947-20160425204735

My thought was that these changes would make those plants useful in levels that are more challenging, because right now, plants that don't have splash damage are pretty much useless in a lot of the levels, But at the same time doing this would make easy levels even easier, so that's why I thought of increasing the speed of slower zombies, to provide a bigger challenge on levels with easier zombies, but doing that would make defensive plants less useful so that's why I would lower their recharge time to balance it out a bit.

Either way this are my ideas and I understand that not everyone thinks the same.