I've been asked why I didn't write anything about Howard Keel. The answer is that I really don't know that much about him -- in fact, until I read his obituaries, I was unaware that he'd ever been on Dallas (I've only seen the first and second seasons of that show). I will say that his film career probably suffered from two misfortunes:
a) At the very moment when he was starting to become a big star, the mid-'50s, the bottom dropped out of movie musicals. Or, rather, the bottom dropped out of solid, medium-budget, quickly-made musicals, the kind that required a guy like Keel who could be a convincing singing hero. Starting in the late '50s, musicals started to become big, ultra-expensive prestige projects, and the kind of musical that Keel had been perfect for -- old-fashioned studio-bound, studio-system projects like Seven Brides For Seven Brothers -- more or less disappeared.
b) Keel's type of legit singing seemed to go out of fashion in movie musicals in the '50s (and even on Broadway, to which Keel repaired for the expensive disappointment Saratoga). Male singers rarely became big stars in movie musicals anyway -- the big male stars of movie musicals tended to be primarily dancers, whereas the big female stars tended to be singers -- but it was even harder to become a star as a singing actor when fewer and fewer musicals were being made that called for his kind of singing.
Pauline Kael has a lot of nice comments about Keel scattered through 5001 Nights at the Movies; she clearly liked him a lot. Alfred Drake the Broadway star whose parts Keel tended to play in the movies (Kiss Me Kate and Kismet were Alfred Drake shows filmed with Keel in the lead), didn't feel that way; his comment on Keel, in the course of explaining why he (Drake) didn't have a movie career, was something to the effect of "The movies had a guy who they thought could play my kind of parts. He wasn't very good." But Alfred Drake would have been pretty damned embarrasing in Seven Brides for Seven Brothers, where Keel not only sings well but does a fine job of making us sort of like a character who is -- deliberately -- written to be rather unsympathetic much of the time.