I have nothing against the other worlds, I just go to them when I need to, not when the host is forcing me to sift. 
...was it to combine all the Other Worlds thread onto one menu? :hoppingma I don't feel like filtering through 500+ pages just to find RL-, DS-, or PS- related threads, especially threads I've been keeping track of.
The Community Management team wanted the minimum number of forums to make the forums work. So the choice was either combine the the old worlds on the 4e forums or combine them with the homebrewed worlds in the previous edition forum. Since you do not like the mashed Other Worlds forums I'm guessing the alternative would have been worse.
The decision was out of the hands of the community, but after Eberron if they update any of their other old publish worlds they will get a forum of their own. Until then they will be combined.
However they are using a general rule of thumb of less than 50 active posts in a 24 hour period is acceptable and if a forum produces more than that each day then there may be need to split it into two forums. This will probably not happen immediately as they are busy with the reorg, but some time after the reorg they may be willing to reevaluate the busy and crowded forums.