The Godfather and Lord of the Rings are great, long movies. Does that mean you shunned The South Park movie or Team America because it didn't last 3 hours? No. Because that would have been ridiculously stupid.
I actually think that LOTR movies are way too long and could be fit into more compact space. That is the reason I don't like them (also that horrendous CGI!). Hobbit movies are even worse because the source material is even thiner and Jackson decided to make three 3-hour-long insanely boring movies, GG.
So you're kinda right. South Park being that short might be a good thing.