That's the whole point of progressive music. Falling into the trap of assuming that, just because you change up time signatures means you are progressive... well, let me just say this.
Prog = Genre
Progressive = art form.
In fact, i'd be inclined to argue that bands who are pushing musical boundaries and doing things that have rarely been done before in this musical form... Folk metal bands like Eluveitie, Tyr, and bands like Agalloch who borrow a lot from the black metal scene... these bands are more progressive than a band like circus maximus.
That is the whole contradiction in the prog genre. Prog bands have to fit a formula to sound prog. The very quote of "odd time signatures are a common feature in progressive music"... the terms "progressive music" and "common feature" simply cannot be used together because then it is no longer progressive, forward thinking music. If you want something truly progressive, pushing the boundaries, check out The End Records. They have many bands that are trying new things, most of them are NOT my cup of tea, but they are few of the truly progressive bands left on that label.
This is why i don't like prog or prog metal. These bands all sound so damned similar because they are "trying" to be prog, which means they are trying to fit the prog mold. It's a hypocrisy. This genre is no different than death or black metal, but these genres aren't lying to themselves or anyone else. Death metal doesn't state that it's trying to re-invent the wheel.
</rant>