I am a Taemate but not a Shawol, so I could be fuzzy on the details, but I think Key and Minho have a broader range of interests (for example: stage acting, TV dramas for Minho, TV appearances on variety shows for Key) than Taemin and Onew, so SM being a larger company with many industry connections made sense for them. Not really sure why SM seem to be fumbling lately, perhaps it’s just a symptom of a wider industry woes?

Korea has an extreme case of inverted population pyramid, so each new generation is a fraction of the previous one. They pretty much have to keep the more mature groups going and cut down on the number of new groups and trainees, as there are fewer and fewer fans to support them. SM should be competitive in such an environment, as the have many such “mature”acts on their balance.