Yes, my background is Software Engineering. However, these days I am a dedicated server provider and also a film producer. I still dabble in doing stuff with servers though. I guess most recently, I used a few as a small 3D rendering farm for Blender for a fun short film project.
There are many reasons for the app to have failed in my opinion and probably laziness is the biggest one. But also the photomosaic concept somewhat requires a large medium for it to work.
With more and more people doing their browsing on phones and tablets, it is really hard to appreciate a photomosaic in its full glory. Really, ideally you print one on a wall. A 36 x 24" poster is alright. A picture within a 5-10" screen, not so much.
I didn't really try to market it much, but based on how few of my friends actually even tried it, I figured there was too much friction in the signup process in order for it to work, and I was too lazy to make it easier. It wasn't a money making proposition in any case, more like something I wanted to see if I could accomplish.
If you're familiar with photomosaics, you can imagine they take a lot of computing power to be created. So having it be successful would have created a logistical problem for me, so I was very OK with it not going anywhere. =)
JoseQ