As a fan of high heels on women/female characters, I say there's nothing wrong with heels and it's perfectly fine that the female characters have them in Em8er. In fact, having them is better for their design and makes them more attractive.
We are talking about polygons and pixels in a video game, and also the fact that there are plenty of unrealistic things in Em8er anyway. So the "realism" and "impractical" arguments are, to put it - a stupid one and completely reeks of selective bias.
Therefore I find it really strange on how everything else is allowed to be unrealistic/fantasy, yet a female character's design/clothing/shoes has to be realistic. Reminds me of Final Fantasy XV a few years ago when the whiners complained about Cindy Aurum's outfit being "unrealistic" and demanding it be censored changed, all while Noctis could summon magic in the form of Shiva to help in certain situations. Yeah, we sure see everyone do that everyday in real life right. The selective application of realism is quite simply pathetic to the point that it's hilarious.
If one is so bothered by female characters "wearing" high heels in a video game then I would suggest perhaps to ignore it.
What I suspect here may be a masked attempt at de-sexualizing the female characters, given that high heels has always been one of the main items of female attire that the Space Jam Weasels have a major problem with.
If the developers/designers decide to heed the "advice" of the Anti-High-Heel brigade regarding the female characters, then I suggest options for both high heels and any boring-flats-that-look-just-like-male-shoes.