space doesn't sell a charter
space does. So do individual ensuite heads.
Therefore, when designing with the charter market in mind, you specify several small head compartments instead of one roomy one. In order to maximize the cabin
space, you make the heads as small as possible. Access to the hoses, pumps, etc. isn't as important, because the boat won't be in charter service
long enough for that to matter- and, in any case, hired help would be doing the work.
A lot of manufacturers do this, because it sells. For cruising- where you have to fix things yourself- I would argue that a prudent designer
will specify fewer, but larger, head compartments. You can always add handrails for bracing yourself in a seaway, but you don't want to cut through a bulkhead to get to the discharge hose when it breaks.