I find that strange since wooly Yoshi is so much slower and it's so much easier to save yourself from mistimed jumps and just flutter jump out of harms way.I'm surprised to hear someone say this because I find YWW's stages much harder. I 100% finished all 54 stages in the original YI, but I'm not sure I have the patience to do the same in YWW. I find deaths more frequent and secrets more obscurely hidden. It's much harder to stay on top of health without the original game's ability to make star eggs too.
Yes, finishing with 100% health on your 1st try is trickier than in YI since the checkpoints don't save your health and there are no items but, unlike in YI, you don't have to collect every everything in 1 go so you can just quickly replay the level afterwards. This will also make you realize how simple the levels actually are.
WW is more frustrating than hard; it does not require as much platforming skill as it does patience to comb through the level. Not a good design philosophy at all.