To answer the question posed by the subject line... it's creep, plain and simple. I say that because I agree 100% with Andy... it is currently illegal to remove the evaporative canister, so the only legal way for it to disappear is via rules change. But if changing a rule in order to make cars faster isn't creep, what is? To top it off, this change could (nay, would) make some cars faster, but not others. What's up with that?
Interesting exchange on secondary butterflies, but I think a couple of points were missed. Those butterflies are exhaust emission devices; AFAIK, their design purpose was to alter exhaust emissions. But sorry, you still can't take them out, because the paragraph as written allows only two types of exhaust emission devices to be removed - air pumps and EGR devices: the butterflies are neither. Oh - and you can block water flow to an intake manifold, which is another exhaust emission control device. Then of course, you can remove the catalytic converter, yet another exhaust emission device. Yes, there are incongruities here.
I guess I might be in favor of a rewrite of this (emission control) paragraph, but I'm just not sure removal of the evaporative canister should be part of it.