If wheels were properly tensioned when built, it'd really not be an issue.
Just looking at the hubs, which requires more machining from the raw cast state? Access, such as machining the "socket" the spoke sits in for a SP spoke etc.
Bladed spokes are in a different category. Namely much higher priced bikes/wheels.
"Round" SP spokes may not work on the automatic wheel building machines because of potential "spinning". Let's face it. Most new wheels are machine built. You're also not going to put bladed spokes on xmart type bikes.