Thank you for posting the first game jam feedback I've ever received. =)
What I was thinking when I designed the movement system was that acceleration is slower when running on slick surfaces, so it is a little harder to get going from a complete stop. Deceleration is also slower, so it's hard to stop moving. I could change these exact levels a bit in the future, or vary them by stage.
Perhaps I could make the dash faster at higher difficulties, since it would make surfaces feel even more slippery, while also adding a tool for more experienced players. 