Marvel getting desperate
Food for thought... my daughters and I collect Hasbro's Marvel Legends figures. I enjoy them because they remind me of the toys I collected in my youth (and I can often acquire the modern versions of toys that were out of reach or of characters who didn't have toys when I was a kid), and they enjoy them because they are representations of the characters they have experienced in animated series such as X-Men: TAS and the 90's Spider-Man cartoon, as well as from flipping through my old comics collection. It's a fun activity for us to share, and most importantly it is something that keeps them off of screens for awhile!
Hasbro is generally very good about staying true to the characters as they exist(ed) in their original media, whether that be specific comic appearances, TV show appearances, and of course the MCU appearance of characters in their MCU toy line. Their changes to characters are often very minimal... maybe a slight change to a costume or something like that, due to the fact that an existing mold that is "close enough" exists (thus, simply a cost-control measure). The vast majority of the time, their toys are accurate representations of their comic book counterparts.
I do understand that the movies are a different animal from the toys, but at their core they are both responsible for presenting these characters in a way that is palatable to the general consumer. Admittedly/arguably secondary to that is their responsibility to present the characters in a way that is respectful to that character's source material. Clearly, the toy industry (or at least Hasbro / Marvel Legends) has determined that their best path to market viability is by staying true to the source material. So why would that also not be true for the movies? Or, put a different and more conversationally-specific way, would general audiences truly decide not to go see a FF movie if the Silver Surfer were portrayed in a true-to-source way (male, nude/smooth, herald of Galactus)? If general audiences would indeed still go see a "true to source" FF movie (which would thus include a very strong female lead in Sue Storm), then what is the purpose of veering off-course with the Silver Surfer's portrayal, knowing that doing so would potentially alienate many of those who would prefer and expect to be presented with a true-to-source characterization of that individual, just as those same individuals would likely purchase an accurate Silver Surfer action figure and pass on a "created just for this toy line" female Silver Surfer that has no source history?