Some politicians may perceive 80% lowers as an issue that can energized their base, but misplaced hype has lead them into an issue they do not understand.
80% lowers are not a gimmick worked out between firearms manufacturers and the ATF. They exist because it is necessary to have a legal definition that differentiates between a lump of aluminum and a firearm, or between and AK47 and a shovel.
If 80% lowers are illegal, then there will be 75% lowers. And if the bar goes a little lower than that, then the plumbing department at Home Depot will be full of precursor firearms. You would think that definitions are central to the business of lawyers, and that they would think carefully before making changes in these areas, but apparently not.