Not sure if this has been brought up already, but it might also be easier for devs to not have to redesign their app logic completely when porting their app to WP10. If all UI elements from iOS and Android get a WP equivalent, maybe some degree of automated porting could even be done. If this helps close the app gap, I'll have all you can eat hamburgers please.
Well, some of the posters here said that Microsoft is changing the UI so it's easier for developers, that it's meant to invite more devs.
I assume that with "it" you are also referring to how easy it is for developers to port apps. I place little faith in those claims.
People not involved in the software industry tend to greatly overestimate the importance of how a
UI looks in terms of how that impacts porting costs. Compared to the costs incurred by each OS having completely different libraries, frameworks, and (less importantly) using different programming languages, the impact of a more similar looking UI is limited. Consider that even with a similar UI, the instructions that draw those similar UI's to their screens are still completely different. What we're talking about here is solely conceptual similarity, not technical similarity. That's not nothing, but for something as simple as an app, conceptual similarity isn't that big of a deal either. How much of a difference do you expect that to make? How long do you think it would take for someone who made, say, Tapatalk for Android, to come up with the corresponding design for WP? I'd say most people on this website could do that rather quickly. That's the difference we're talking about. Not more.
IMHO the view that this would make a substantial difference can only be maintained through ignorance.
There is an entirely different angle which might make more sense. We've heard about MS potentially attempting to provide a way for developers to develop an app but once, with the ability for that single app to run unmodified on all three platforms.
That is not called porting, nor would that directly affect any of the Android apps that already exist, but having a very similar UI is probably the only way to get that to work effectively. If MS is in fact working on that ability, then you can bet your bottom dollar that's what's behind these UI changes. Not porting costs like some are speculating.
And one last thing. I work in the software industry and have over the last few months talked with multiple CTO's who's companies don't provide apps for WP. They don't all have the same reasons for not supporting WP, but none of them cited porting costs as a reason either.