There have been a lot of bands with weird names through history, but music lovers don't care as long as the music is good. If they were named smile, people wouldn't have said that songs like We are the Champions and Bohemian Rhapsody weren't good. Smile would have worked just as well.
The name Smile does not seem like as cool of a band name as Queen. However, as long as the band's music was the same, it would have been very popular with listeners! Most fans of Queen love the band for its awesome music. Yes, we are used to the name Queen, so its hard to imagine them playing under a different name, but the music would have still been popular.
The band name "Smile" denotes a cultural connotation that already has been used- mainly, a positive go-lucky band name. This cultural connotation was not in demand in the 80's. Whereas the new band name captured the spirit of the 80's and met the demand for edgy rock bands, or at least promised to.
No, Queen's songs would not have been popular if the band remained named Smile. Even with the brilliant voice of Freddie Mercury, Smile as a band name would not have conveyed the same strength that the name Queen does. Quuen as a band name is much more memorable and appropriate for one of the best rock bands of all time.