Stringsinger, I think that we make a huge mistake when thinking fun and seriosity to be mutually-exclusive contrastives.

The "seriosity" of an instrument can be defined by various criteria. One definition is "optimised for sound (according to present-day aesthetics) and virtuosic technique in all keys" - many folk instruments fail this. A second criterion is "historically accurate for the music played". The third criterion: "representing a culturally significant tradition", actually provides a degree of seriosity proportional to that significance.

Needless to say that there is hardly any non-serious instrument. The cheap chirpy plastic strings have created their own culture, like tin whistles and cheap cameras.

The fiddle/violin is considered the flagship of seriosity, particularly among folk instruments. Note however that Stradivari would hardly recognise the sound his instruments produce today, because they have been altered considerably.