Thanks for the feedback ! You are not being harsh, you are being constructive, and that's good ! :)
It was my intent to make the whole game playable without collecting any coin, and coins to be a little detour to help those having trouble, but as I didn't work enough on level design I failed to do that. As I decided on having 7 levels it required me to have a 1 second clear time on average per level and that limited me heavily in my level design, especially for making vertical levels, hence the addition of coins.
Glad you liked the concept though !