I don't think switching tech is quite ready for taking over existing infrastructure. One often overlooked reason comes down to: fusing!
DC is very troublesome to fuse. Arcs need to be quenched with a combination of cooling air blast and pinching magnetic fields. AC's zero crossings make switch opening (under load) and fuse clearing much simpler.
I suppose you could argue that all those systems could be semiconductorified as well, but things get really out of hand, really quickly. Instead of merely replacing transformers with DC-DC converters, you're also adding protection circuits (that have to be at least as large -- because they have to handle the same power, or more), switches, current limiters and so on.
And you still need transient protection, because remember, while all of this stuff is going on, you still need to withstand direct lightning strikes!
So the combination that we have today: AC, transformers, fuses, switches and so on, really is a remarkably robust and efficient system, even if we scrutinize it with current technology.
If, a century ago, someone had said, "they'll never improve on this stuff", they might be a fool for saying so. But as it turns out, they would've been startlingly correct!
Tim