It makes sense if you have significant code that's not UI-related.
IIRC, Photoshop is implemented this way - there is little code reuse at the UI side, but the bulk of the program is platform neutral. I had Photoshop (2.5) running on IRIX on my desktop for some (very fun) time.
I too had Photoshop running on IRIX way back when. As a matter of fact, it saved my butt on a job where I had a massive file for a poster design, and it would keep crashing on my PC whereas on the O2 with an older version of photoshop it just chugged along slowly but surely. It was an exercise in patience, for sure, but it also ensured I could deliver on the job and ultimately get paid!
IIRC, Photoshop is implemented this way - there is little code reuse at the UI side, but the bulk of the program is platform neutral. I had Photoshop (2.5) running on IRIX on my desktop for some (very fun) time.