I think this is it. Jane intended for him to be commentary on a certain type of person. He's not really meant to be sympathetic or even fully-fleshed out. He's a stand-in for a type...I think if Mr Collins weren't so clearly meant to be striving for money and position in society, things like practicing a compliment could be read differently. But as is, I think he's just simply meant to be a man reaching for a grandeur his position and personality do not allow for.