Yeah, having every single icon using the same shape is what I meant by trending toward iOS design ethics. The distinctive shapes worked as a visual aid in finding the one you’re looking for in a single glance; unlike you I don’t find that to look messy. I have more difficulty quickly locating an icon when looking at an iOS home screen because every developer is forced by Apple to use the same exact shape, there is more scanning involved, more scrutiny—and overall I have noticed there is less variety in design.
Not every good idea can fit into a rounded rectangle, which means a lot of good icon ideas get lost, and there are certain things that just work better when stuck in a shape like that, and other ideas that are a very poor fit. Like, for example, Obsidian’s current icon. I love it! It’s a fantastic icon, but frankly it’s no good for iOS (and now Mac), as the best you can do is just toss it on a matte background. There are billions of ideas like that that are now gone. To me that’s a much, much bigger problem than whether designers use a little drop shadow or pebbling.
That aside, there is potential for distinction between platforms, I agree, but I bet the human tendency toward finding the easiest path causes more homegenisation between platforms in the end. Some might like that, but I find iOS’ aesthetic to be very unsatisfying—and that includes things like rigidity in icon shapes.
Ah well, I’m just grumbling at this point. I’ve left Mac for Linux some time ago, but I do still have a bit of an emotional connection to the platform I suppose, after twenty-five years of using it. 
Anyway, it’s a nice design; didn’t mean to hijack your thread!
