I think that the quaint wackiness in HHTTG is simply a cult thing; it provides its fans (plus a broader body of geeks) with a body of references they can draw upon in order to communicate. Like this 42 thing. You don't need depth for that, or even humor that is rib-splitting. I think that the work simply holds a charm for some people, which may be all stylistic; it's okay to dig style. Just like quantity can be a quality of its own (who said that, Stalin?), style can be a depth of its own.