Skateboarding has definitely grown over the past decade and is doing well again after the 90's death/lull.
However, from a business decision is was a normal progression for the series.
They were trying to pull in the THPS crowd which is not skateboarders in general.
If you look at THPS for the most part it is a platformer with a skateboard motif (minor exceptions here and there).
Trying to get them to enjoy Skate meant allowing more leeway into arcade style gameplay.
This upset many of us, but having worked in the industry I understood the change.
I myself still enjoy certain aspects of OG Skate, Skate 2, and Skate 3.
Skate 3 is what I play the most simply because I have more options.
Long ago I did a write up on the EA forums of how I would like a remix game done.
To me OG should be the core, but 2 and 3 definitely have some nice features.
Play what you enjoy till you don't enjoy it anymore.
Hell, I still play Thrasher and that game is 12 years old almost.