The revised view of TR is probably due to two things:
(1) The fact that the modern Republican Party thinks the US would be a better country if the entire Progressive Movement had never occurred.
(2) The modern Democratic Party, while sympathetic to TR's reformist zeal and concern for the environment, is put off by the fact that the man was a horrid racist who more or less felt the US needed to engage in the sort of imperialism Europe was undertaking at the time, even moreso than we already were (in Cuba, Central America, etc).
Basically, this. I do like TR's energy though, and wish that progressives today had that kind of zeal.
