I agree with wa8yxm.
Even for new rigs I think the current trend has been seperate. Given there are so many ways to skin this cat seperate allows much more flexability over time. Examples:
1) My new distribution box can be configured for either 30 or 50 amp service. I maintained the original 30 amp service with mine. An alternmative with that panel is that if I had two Air Conditioners, one circuit could control the front AC and the primary AC distribution while the other circuit could be used for the 2nd AC distribution (2nd side of a 5K or greater generator).
2) If you have a generator you may also want to add an AC Transfer switch.
3) If you want to convert to a Inverter/charger rather than use a converter/charger it is easier to change over.
4) Not only are DC fuse types used in todays distribution boxes easier to work with, you can also get versions of them that "light on failure" AS WELL AS "Circuit breaker" versions of them (they plug into the existing fuse slot). The circuit breaker version can be purchased in either as "auto reset" or "pushbutton reset".