That's great news. The argument that hiding taxes and fees (especially "resort fees," which now apply to every tertiary suburban hotel) is anything other than an effort to mislead consumers doesn't pass the laugh test.
I recall some whining, maybe from the airlines, about how it was important to advertise fares without taxes included because that way passengers would be able to see/appreciate how much the government was taxing travelers. To which the obvious answer was: If you want to drive home how much the taxes and government fees are, highlight that in big, bold type — just like Spirit does when it displays, bitterly, the "Government's Cut."
If someone has a strong argument for why vendors, especially in travel, should be permitted to market a price that is below what a consumer must pay to get the product, I'd love to hear it. Especially when the advertised price excludes fees imposed by the vendor that are retained by the vendor. Until then, this new Marriott pricing display sounds like a great change.