you do not decide the spirit of this game just because the code is gpl'd. .maps dont help beginers to do anything more than copy. if a fatal flaw is found then tough, get the original mapper to sort it out.
...FART
Actually, I've learned a lot looking at other mappers work. Original mappers are not always available, marsbase is an example. How you can say that a game that is open should have parts that aren't open is beyond me. It seems you should realize that it is in fact you who does not decide the spirit of the game. That the code and media is open seems to have predetermined the spirit of the game, not me. Examples of the opposite seem to be the exception, not the rule.
Incidently, in 4 or 5 years when tremulous is on version 1.2

the original mappers may not be available. Alternatively, there will probably be lots of people willing to dig into the map to resolve any serious problems that are found, just like with the tremulous code. Or to modify a map so that it may continue to work with newer versions of tremulous.
People actually like to contribute and help. and to help things like maps to live on. Wanting mappers to leave that possibility available is not so terrible.