I do agree, it's time consuming to create art assets. Even trying to make character sprites takes time though in my case I actually edit the graphics (creating the parts in the Character Generator and editing/recoloring them in paint.net). My characters are 72x48 and are based on the default MV graphics. Here are three I've made:
Interesting to see even Lawmage Academy include slime monsters. Of course, slimes are one of the default enemy images included in RPG Maker MV so any MV game set in a medieval fantasy setting will probably include them.