I'm right there with you wanting much higher variety and variant options for tieflings, from the ground up. I'm kind of sad that we never saw the texts for abyssal and lothic tieflings outside of unearthed arcana, but yes - we should absolutely have a much greater variety of options for our tieflings' appearances.
I suppose it would be relatively easy for them to include the human heads and bodies as options for tieflings, for starters. Then you could just have a weird eye color or whatever.
