[johnyzee]

There are solutions that redirect actual sunlight from outside, into dark interior spaces. They use them in many modern metro stations, and they work pretty well to get the feeling of actual overhead windows. AFAIK some of these solutions successfully channel almost the entire spectrum of real sunlight. I always feel that this is way under utilized - I could hardly name a building that wouldn't benefit from additional sunlight in some of the interior spaces. The systems are currently quite expensive, so that's probably part of it.

As for plumbing, like you I also speculate if they could not just do a raised floor, or possibly inside/along walls, to increase the reach. They already do this in some renovations of very old buildings where they want to create a large central kitchen (resulting in almost horizontal plumbing that clogs like nobody's business).