At what point? When iOS marketshare hits 20%? 15%? 10%? I think my basic point is that if an average iOS user uses apps more than an average Android user, then the marketshare of Android needs to at minimum have that much of an advantage over iOS to make up for its users barely touching apps. That's at a minimum. But moreover, as an App developer, I think I'd rather have 10 million loyal fans using my app 1 hour a day than 60 million using it 10 minutes a day. It's clear who is using my app in a deeper manner, and I would work on adding new features to cater to those who actually utilize my apps features.
If you look at Twitter, how many people are tweeting from iOS versus Android?
If you look at Foursquare, how many people are checking in via iPhone vs Android?
If you look at Facebook, how many people are posting photos via iPhone vs Android?
In all 3 categories, what I can see is it's iOS.
At work when I see people checking their phones during meetings more than half of those are iPhone users. Amongst the whole manufacturing engineering group at our office, with ages 20-early 30s, ALL had iPhones. This is a target audience that uses phones and apps actively. I can bet you these guys use their phones far more in terms of apps than 50 year olds.
Honestly, looking at those statistics if I wanted to target an audience that will use my app more, I think I would do iOS first. Even if my app is free. You want to be popular? Get an iOS version out. Even my friends who develop for Android, they desperately find an iOS developer ASAP to help them out and launch as soon as they can. Meanwhile I see iOS developer friends take their sweet time. Wait 6 months even before actually starting to port over. It's just not a big priority.