I'm not sure I understand your point. Do you think the majority of spaniards would support amending the constitution to allow for a region to declare independence? Seems really dubious to me. And if not, then why blame the constitution?
I mean a Constitution is not, and must not be, respected if it goes against the will of a big part of the population.
A state constitution must offer a framework which is interesting for all of its peoples and territories: if big groups of people do not see the point of it, it looses its validity.
