I've said it before and I'll say it again...if the BBs could have seen fit to give "River Song" a life in context of the band, even with Endless Summer in play to bring back their classic period, they might well have bridged the gap and been able to have it both ways. In 1974, this song had a chance to make it big as a BB song. The band could ROCK, folks!!
Presumably this was part of the main plan Dennis wanted to get back to...