Smart move by them if they did. I certainly would have... Plex on Xbox One is a huge advantage for them over PS4. If they didn't make it exclusive, they really should be trying to do so.
I would think it would be in the interest of Plex to be on as many platforms as it possibly could.
I would think it would be in the interest of Plex to be on as many platforms as it possibly could.
I'm sure there are at least 2 factors in this decision:
1. Developers - do they have even people to sink the time into another application which they have to create and support.
2. Sony - do they allow application development by 3rd party's and how accessible is it (I genuinely don't know, I don't have a playstation).
A big part of why they likely went for the xbox one was the universal apps that MS has been pushing, they likely got to reuse a good bit of backend code from the Windows Store and Windows Phone applications. That would have cut down a bit of the development time and gave them a head start, where as with the playstation application they would likely be starting from scratch with a completely different api.
In short, if it was a simple decision, I'm sure they'd jump at it. :)