The 1.0's are lacking in mid-range. I have a pair of "over-the-ear" and a recently purchased pair of the "on-ear", and the soundstage seems much thinner on the "on-ear". The 2.0 are an overall improvement in mid-range regardless of "on" or "over" ear.
I can see how you'd have that initial reaction, though. The Momentums are much more neutral compared to the V-Moda's and the Urbanite XL's. You're probably much more attenuated to a "bassier" headphone. At the end of the day, it's all down to your personal tastes in sound signature.