Your post explains why there was overwhelming support. Most people only look at the issue on a surface level, so while voting against the bill might make sense in a principled sense, it politically is more advantageous to support something that looks good on the surface.
Massie and Amash explain why it's not a good bill in principle. They tend to vote according to principle, even if it isn't politically popular.
Trump will probably pass the bill, because vetoing it would be too easy for the media to spin as racism. Granted, they've already called Trump racist for so long that it might not have much of an effect at this point.