Your point about hard wired "set it and forget it" technology is valid, and probably preferred by many.
Makes you wonder why charging/maintaining all batteries from shore power isn't standard functionality from the factory for all motorhomes. Considering some/most upfitters go to the trouble of adding a battery separator and a combiner (battery assist) switch to boost the chassis battery from the coach batteries when necessary. Depending on the make/model of motorhome, sometimes the coach and chassis batteries are sitting next to each other. Can't make it much easier than that, as far as charging everything together. Yet only certain rigs come with this capability, as pointed out earlier in this thread. Maybe that's the problem. If the coach and chassis batteries are farther apart by design than they are in some class A (under the inside steps?) rigs, maybe it's not worth the effort, if you're already installing the battery assist option.
I noted that the Winnebago One Place Systems Monitor Panel on the 2018 Navions have the ability to check the status of the chassis battery as well as the coach batteries. Interesting feature. I have to research that one.
I suggested using the coach's AC outlets when on shore power as a power source for a portable smart charger/maintainer as an option that didn't require the user to know anything (except which DC outlets were which, as pointed out by Gary) about battery polarity and running and connecting the wiring. Mostly for the safety of the "electrically challenged", like me. It's the option I chose because it was completely DIY, simple and safe, and that's worth the extra $10 to me. You can use the BC8S in other vehicles too, because it's not hard wired to the motorhome. Flexibility of purpose?
As they say, everyone's MMV.