Roth makes more sense when you expect your marginal tax rate in retirement will be greater than or equal to your marginal rate today.
Note that for your marginal rate to be higher, you're probably going to need a higher taxable income in retirement than you have now. For that to happen, you're going to need some savings in traditional accounts and/or a pension, since Roth withdrawals generally don't count as income. Therein lies the reasoning behind the general advice to prefer traditional: the more money you have in Roth, the less likely it is that putting more in Roth is going to be an optimal decision. Roth can be great when it's the only tax-sheltering option available (if you have too high of an income to deduct traditional IRA contributions, or if you have the mega backdoor available at work), or if you're in an unusually low-income year, or if there are other special circumstances in play. For most of us, we should do as much pre-tax saving as we can.
One other consideration is whether you are likely to inherit any money in pretax accounts.
Sure, maybe, if you inherit a bunch.
If you inherit a $1 million traditional IRA at age 50, you'll have an RMD of $29,239 that first year. That's not going to put you in a very high tax bracket on its own, not right away.
Suppose you get to age 70 with the inherited IRA still worth $1 million (your RMDs and any additional withdrawals took out the growth but nothing more). Suppose you also have your own traditional IRA with a $1 million balance at that time. Your RMD for the inherited account will have grown to about $70k at that point, with the RMD for your own account starting out at about $36k. Now we're getting to the point where being in a higher tax bracket than you were in while working is a real possibility.
How many of us actually expect to inherit a $1 million IRA, though? My parents did pretty well for themselves (as far as "normal" age retirement goes), and yet they still aren't millionaires. Furthermore we all hope they live long enough to spend most of it before they pass away, and anything left will be split three ways anyway. So how much inheritance am I planning to get from them? I'm not factoring it into our plans at all. They could leave us a six-figure amount, but it could just as easily be nothing at all.
If you are reasonably certain you'll get a $1 million IRA inheritance, you should definitely take that into account when estimating your retirement tax bracket and make your own retirement contribution decisions accordingly. Keep in mind that in the above example it still seems pretty doable to structure things so that you never exceed the 12% bracket. A single person who takes the standard deduction is still in the 12% tax bracket all the way up to $51,675. Double that amount for a married couple. If you pull out more than the RMD from the inherited account early on, you're much less likely to have your RMDs push you into a higher tax bracket later in life.