i dont think the buying out wcw and ecw is the problem, its having 3 seperate brands within the one company thats the problem. ever since raw and smackdown became two seperate entities things started to decline. now all brands rely on 4 or so major stars (HHH, HBK, Cena, Taker, Batista, Rey) and about 8 lower status stars (Hardy's, Mr Kennedy.......Kennedy, Umaga, Carlito), who all continually fight each other over and over again. plus with only one night a week to develop the storylines it always seems that they have too many stories but not enough time. add to that, little rotation of the rosters, being only done after wrestlemania, means that we end up getting stuck with the same ol' stories or rivalries again.
almost everytime they have done a cross brand rivalry its been pretty damn entertaining, with the exception to the lashey/umaga and goldberg/lesnar type feuds.
back when it was still good, we had the rock, mankind, austin, taker, HHH, angle all feudining with each other, but they had time to develop the feuds, plus they had a bigger pool of second tier superstars to choose from to make up the rest of the shows.