I can see both sides of this one. On the one hand, as you say, people DO have guests, and then it's nice to support them in comfort.
On the other hand, sometimes even friendly people don't have guests nearly as often as they think they might in the boat-shopping phase - especially if they are newer to cruising and don't realize it can be somewhat unpredictable at times.
When we went off sailing, dozens of people said they would love to come visit, and we encouraged them. Ultimately, we had visitors twice. Once a couple, and the second time the woman of the same couple, but solo.
I can't blame the others though. It was an effort to come and our schedule was subject to weather and other unpredictable things.
Now, we were sailing, and carrying along another 12' of boat "just for guests" would have had significant consequences. Some financial; but more than that, physical. Bigger sails, heavier lines, etc. Plus more draft usually, which would have limited us in the places we spent time. We saw many people do that, for guests once per year or less (which is fine, if chosen consciously).
Someone cruising such as Wanderer right now is close to friends, schedules on inland waterways are slightly less weather dependent; and with his particular boat there doesn't look to be much if any downside to carrying the guest space along all the time (he probably would have wanted about the same sized boat just for himself).
I'm *not* one to say don't plan on guests; but I would say do understand that in many cases they may not come in the numbers you'd think (especially think about this if new to the whims of boating vs. purely land or commercial air travel). And then also consider how a larger, deeper-drafted, or more expensive boat might impact you at other times (may or may not be an issue). And too, what sort of luxury level would you or your guests want or expect.
Sorry for the tangent. I think the "may not be as friendly" got me going