I think they're more aptly described as the illegitimate lovechild of a railgun and a crossbow. The only thing that makes them blaster-like is the so-called 'plasmoid shell' the bolts are coated in upon firing.

That does beg the question though - exactly how useful is a bowcaster? From what I understand, they can only fire a single shot at a time, before they need to be recocked in a manner similar to a crossbow. Are they more accurate than a standard blaster? Better able to pierce certain kinds of armor? Less likely to cause a fire that, among the wookies' ancestral trees, could prove disastrous? Just plain cool-looking, and thus more a matter of personal style than of utility?

...I'm leaning towards that last one, personally.