Not at all - I think it's ok to invent languages, period. Little or huge, DSL or general, using established syntax or creating new ones - making them is good. The results can be bad (and frequently are), but that's to be expected of every process.

Knowing different languages just helps in seeing syntax for what it is: another level of abstraction, not a set of rules cast in stone. You can come at the same conclusion with a proper university class or with any number of other means - I mentioned learning languages just because that's what worked for me.