I don't think they are becoming that way because of how many there are (although I hate when they have 2 in a month), it's a decision they've made. They intentionally book their feuds to last longer like they did years ago. Before the Attitude Era guys would face off for the best part of a year but then when the WWE developed or signed up so many extra top level wrestlers every feud was fresh, there were limitless possibilities, so you could succesfully build an interesting feud that ends in 1-2 months.
It was because of all these new stars that they implemented the draft system and now there aren't enough stars per brand to keep doing that. If you have everyone feud with everyone for 1-2 months, then even if you keep bringing up new talent every possible rivalry is done with in a a couple of years. Account for faces and heels being kept seperate, only the very finest mid-carders being allowed to work with the main eventers and it just gets stale way too quick unless you have people feuding for months on end.
This is why I don't care for the WWE as much as I used to, I know heading into a PPV that the result with be inconclusive and nothing but a set-up for the next one (and the one after that). TNA build more interesting feuds on paper to me, but they ALWAYS blow it with a ridiculous finish (Foley and Sting winning anyone?), and ROH suffer from the fans knowing who wins 3 months before the damn thing airs (plus they've taken to headlining them with tag matches which in my opinion sucks, they should have a major, major one on one title match).
I don't buy PPVs (aside from Wrestlemania) but given the business model of all three companies I don't think I would if I did, unless it's a BIG show, you know you are going to feel robbed of your hard earned cash.