No real reason in particular. Looks like some more senior 190 Captains are moving to the Airbus.

Also many 190 FO's head to the Airbus once the 2 year lock is up. There was a lot of hiring 2 years ago so those guys are taking the transition.

Totally depends on one's preference...Airbus is comfy, fewer legs, higher pay and generally speaking nicer layovers....but has the dreaded red-eyes.

I know plenty of guys though who are just fine on the 190 and prefer the higher relative seniority and no redeye flying. But no, there's nothing sinister driving the movement. Hope that helps.