Are you seriously comparing Tom Cruise, one of the biggest A-list movie stars in the world AND for whom all kinds of logical rules are broken on behalf of his real-life 5'7" stature, to Shonta McGarty, whose last starring role was ... (checks imdb) ... the tv series EASTENDERS?
A-list Hollywood stars have what's called "drawing power". Tom Cruise's presence (wacky off-screen antics aside) alone ensures a major motion picture even gets made in the first place.
Shona McGarty has even less drawing power than Gal Gadot (who has very little of her own), which is one of the reasons why the cinematic Wonder Woman is being soft-launched in BATMAN V SUPERMAN in 2016 instead a hard-launch in her own solo movie in 2017.
Wonder Woman has been getting taller, not shorter, in the comics. Her height is one of her visual trademarks. Lynda Carter was 5'8"/5'9" (without heels) in the 1970s WONDER WOMAN tv show, clearly taller than the average American woman. Gal Gadot, at 5'9"/5'10" (without heels), is taller than Lynda Carter. Shona is 5'3" (without heels), shorter than the average American woman.
WB will not cast a shorter-than-average nobody with zero drawing power to play Wonder Woman in any live-action medium, any more than they would have cast Christopher Reeve if he had been 5'7" in height (since he was also a nobody with zero drawing power of his own at the time) instead of the 6'4" he actually was.
Hair color can be dyed or wigged on. Eye color can be changed with contact lenses. Body shape can be altered with workout and diet (among other options). But height as a pre-requisite is a lot harder to get around, especially if you AREN'T an A-lister already.
Personally, I would have gone with THE GREAT GATSBY's Elizabeth Debicki, who stands 6'3" (without heels), is 24 years old currently, can act and has the face.