The fact operations that modify the state of the Web should only be allowed during a POST request is part of the Web axioms, as describe in Tim Berners-Lee's notes.
So, although I'm almost sure this has not been implemented for this reason on purpose, it forces non-knowledged developers to respect this rule, and I think it is positive in fact.
Also, on a sidenote: I think something additional has to be found... Tokens are not more secure and can be tricked and bypassed (don't forget CSRF starts with the assumption that Javascript code can be inserted ).