The brands you mention aren't the top of the Marriott range (in the "Select" group), and so I am not sure what the appropriate expectation is. I presume that each of those brands has a "Standard" sofa bed that the property/franchisee buys, so if you are unhappy with that type of sofa bed (or even the main bed type) you need to change the brand, or perhaps continent - if you're an area of the world with larger family groups traveling like Asia or the Middle East there tends to be more attention paid to extra beds in rooms. I've stayed in Marriott brands in Thailand with bunk beds and other cool options for families before for example.

From my own experience, I use sofa beds with my kids sometimes (often in a suite as an alternative to a double bed), the youngsters tend to be fairly happy with them, but we are normally in Marriott, Renaissance, St Regis, W, considered "Premium" to "Luxury" (and more often than not outside of the USA) so the comparison may not be entirely fair. Extra roll-away beds seem to be standard across the globe and are perfectly fine, if pretty small for more than one person, or a full grown adult.

This image is quite helpful to showcase the different brand positioning, and hence why even the primary bed isn't as good: https://www.hotel-development.marriott.com/brands

Marriott Brands, and hence why your Sofa Bed may not be luxurious!