You can fit two roomettes into the space of one bedroom, roughly speaking. So you have a good balance when (a) you are more-or-less filling the trains, and (b) the bedroom is selling for twice as much as the roomette. Whether this is happening on particular trains, or whether they are out of whack one way or the other, is a big-data question and I don't have the data.
Anecdotal evidence from looking at Amtrak.com at various times tells me that sometimes a bedroom costs more than two roomettes, sometimes it costs less than one roomette, but usually it costs somewhere in between. This indicates that the roomettes are *typically* more profitable. But that's just typically.
However, there are passengers who won't take roomettes and will take bedrooms. So if there are already enough roomettes to meet demand -- if extra roomettes would mean empty roomettes or lowering the price -- then the bedrooms are better to have than additional roomettes.
This is a complex, situation-specific analysis. If sleeper demand were really high, it would make sense to have all-bedroom cars and all-roomette cars, and you could assign (say) three roomette cars and one bedroom car to a given train, but sleeper demand has rarely if ever been that high. So you have to pick a ratio and build your car with that ratio. Modern cars also require one handicapped room each, which pretty much has to be the larger sort.
That said, the Auto Train has a few "all-bedroom" Superliners (actually 4 / 10 / 1 / 1) because it was expected to have more bedroom demand and less roomette demand than normal. And the transition sleepers are all-roomette. So it is possible to do some fine adjustment, if you really know your demand pattern.
In general, the Viewliner II with the 10 / 2 / 1 ratio of revenue rooms probably has too few bedrooms (and they tend to run *very* pricey). However, the Superliner with a 13 / 5 / 1 /1 ratio probably has too few roomettes. The the transition sleepers (all-roomette) probably makes up for it to some extent. If you tried to replace two roomettes with one bedroom in a Viewliner II you'd likely end up with too many bedrooms.