Democrats in charge of the Legislative and Executive branches of the US government will lead to increases in the tax rates for anyone of medium to high net worth (unless you have political pull to get your own tax breaks).
If the tax rate for people with a net worth above zero goes up in the future (in order to support those needy folks whose net worth is below zero, of course) and that increase is such that the tax rate on YOUR taxable IRA distributions (because you have assets, and the government needs them to increase their power base) is, say, 95%, but they can't get their greedy fingers on the Roth part because I already paid on the tax on that, then I win. Not saying this WILL happen, just that I diversify just in case. I don't consider it a "fascination" with Roths, just a tool in the box.
Been drinkin', forgive the syntax. YMMV, etc.