IIRC the Gulfstream 500 and 600 have active sidesticks that are electronically linked. No need for a heavy mechanical connection.
I find it hard to believe it was a technological reason for airbus not including it. The electronic technology surely existed when they were building the A320. I imagine they just didn't think it was needed.
Now the industry says it's needed, so hopefully the next Airbus jet will have it.