Admittedly, the term is unavoidably subjective. But what I like about them is that they are distinct, and that each one has character. Honestly, the fact that they looked like pictures I could find in a child's book is the main part of what I like about them: they have simple ideas ("a bird") and forms so distinctive a child could tell them apart.
A conputer interface does not have those. You need to track the cursor and then decide how you want to move it. There’s no muscle memory. And no tactile perception. What’s left is visual differentiation and it should be slightly exaggerated.
The problem is that you can go too far here, and it is in fact reminding me of: