JEAN HARLOW, can't dance or sing and her dramatic acting limitations are quite evident and are more suitable too light comedy. Fortunately the supporting cast led by William Powell and Franchot Tone save the day. Six (6) Stars IMDB.
While the OP is an idiot for insulting Jean Harlow's acting abilities, he is right that it's odd that they would cast her in the first place. She couldn't sing or dance, so why put her in a movie where she would have to sing and dance?
According to the book William Powell: The Life and Films, Joan Crawford was originally cast (which makes sense as she was a dancer) but Selznick decided to cast Harlow to capitalize on her romance with William Powell. There's probably some validity to that as this kind of role wasn't what Harlow would normally do and was a bit out of her realm solely because her dancing and singing skills weren't strong. Her acting however was fine. This wasn't exactly Shakespeare but I felt she handled drama well.
The supporting cast was superb. William Powell is always great as is Franchot Tone. I also liked Rosalind Russell's performance.
There's also a story that says Selznick and the studio wanted to capitalize on the fact this story was similar to what she'd gone through in real-life. She refused to take the role but Powell convinced her to do it rather than risk suspension.
In regards to it being a musical, that was an afterthought. The movie was in post production when the studio decided to turn it into a musical. Supposedly, all the musical parts were filmed after the fact and edited into the movie.
Ms. Harlow's singing and dancing abilities are irrelevant. She wouldn't be the first or will she be the last entertainer who couldn't carry a tune or cut the rug. The audience's interest in them goes beyond what they can do. It may be their looks, or their charm, or something intangible; not everyone has 'it'. That's the reason some very technically talented people never make it while less talented ones do.
Woman, man! That's the way it should be Tarzan. [Tarzan and his mate]
I wonder where that story came from that making Reckless into a musical was an afterthought.
According to Eve Golden in her great bio of Harlow, Platinum Girl, the movie was always a musical. Joan Crawford was set to play the lead, and the songs and choreography were "arranged especially to suit Crawford's talents." Jean replaced her "[O]n the same day the Bern investigation was finally closed," referring to the recently re-opened examination of Jean's second husband's 1932 suicide.
Jean's character being a singer and dancer was a major plot point. After all, the script was based on Broadway star Libby Holman.