WADR, not widely held within a small subset of affluent Americans, many of whom are millionaires or multi-millionaires and many of whom (or their heirs) will benefit from the status quo. Generally top 1% or 2% here so to conclude based on this small skewed subset is foolish. Not many Joe Six-packs on this forum.
Definitely true, and it's why I voted as I did. Unless paired with other tax changes, the proposal is not in my family's best interest. But that's also how we vote at the ballot box - everyone votes for who / what they think is in their best interest overall, we get the government we vote for, we see what they do, then we repeat two years later.
The tax code we have is a consequence of all that, and people generally favor the tax code that benefits them and taxes the people over there. NIMBY.
Yes, the step up in basis probably disproportionately benefits the wealthier. But there are tax benefits that benefit lower and mid-range taxpayers (the Joe Six Packs) too that are phased out for upper income. We have a whole thread on what those cutoffs are. But let me just list several off the top of my head: AOTC/LLC, ACA subsidies, ACA repayment limitations, progressive income tax brackets in general, EITC, CTC, Saver's credit, the progressive taxation of SS benefits. FAFSA and college aid in general is in there too although not an income tax. What is your tax loophole is someone else's sacred cow and vice versa. There are approximately 350M definitions of "fair/best tax code".
In other words, if we changed the question to "Should we eliminate the [child tax credit || 12% bracket || AOTC] ?" I bet 70% of Joe Six Packs would vote against such ideas. They'd probably also take umbrage if you described it as a loophole that costs the federal government money, and come up with good reasons for keeping it in the tax code.