Many Florida residents have their second set of pipes running through their attics.
PEX may not have the lifespan of copper, but it sure is easier to repipe.
When/if I remodel my bathrooms I have to have this done due to my existing galvanized steel pipes being horrendously brittle and filled with 70 years of gunk. Ah, the joys of a house built in the 1950s in Florida.
Yes, this is the standard now for an number of reasons:
* because it is far easier to cut damaged sections of PVC on site and assemble replacements than it is to cut metal piping
* PVC is wildly less expensive than the equivalent length of metal piping, because it is used in a huge number of applications
* PVC is non-reactive and does not corrode like metal
and lastly, threaded pipe connections significantly decrease the throughput of a pipeline, reducing available water pressure at the endpoint. It is basic best practice to limit where threaded connections are used so that you can maintain uniform pressure across the whole unit.
So yeah, you're right, the new methods and parts make for very fast construction but the maintenance and repairability/reusability is trending toward zero.
Just like everything else these days, I guess.