> ignoring the platform's established design language and UI conventions is still wrong, and not taking advantage of the user's preexisting knowledge about how to use their device is a wasted opportunity at best, insulting at worst.
What valuable preexisting knowledge is ignored if you make your button text readable instead of being blurred with the glassy background?
Consider the simple case on a desktop OS of how to arrange the "OK" and "Cancel" buttons on a dialog box. For an experienced user of the platform, it doesn't actually matter at all how legible your button labels are, you're going to cause problems if they're in the wrong place. The platform conventions when used properly allow the user to entirely skip reading those button labels.
Obviously, if Apple's committed to taking their UI in the direction of illegibility again, then deviating from their new recommendations may be worthwhile. But the UI design should start by complying with platform conventions, and only break those to the smallest extent necessary, with good reason (which doesn't usually include anything about your app's brand identity). And hopefully, Apple can speed-run the kind of changes they did over the first several years of OS X as they toned down the initial excesses of the Aqua design.
> The platform conventions when used properly allow the user to entirely skip reading those button labels.
No it doesn't since you don't know whether the app is following that convention, so you need to read the label. Besides I don't think it's even possible to avoid reading a short label while looking at it.
> Consider ... how to arrange the "OK"
This isn't the topic, though, this is:
> Apple's committed to taking their UI in the direction of illegibility
> which doesn't usually include anything about your app's brand identity
Do you have a good example here as to me dentity in design is mostly about color theme and maybe a few shape tweaks, which has almost no usability impact?
Or that on Apple platforms, you are not supposed to use "OK" as a button, but rather the action it is going to perform (e.g. "Delete").
Using non-standard labelling _and_ putting buttons in their non-standard order is a real issue.
Not to mention that on some platforms the position of the buttons may be specific to localization, e.g. they may switch order if the user's language is set to Hebrew.
On Mac, the coloring indicates which action is triggered by default with the keyboard - one of the first things to go if you stylize the UI yourself.
These and all the other inconsistencies add up until you have something like the iOS Youtube app, where IMHO the UI is just complete nonsense. Just because you are full screen doesn't mean you can redefine fundamentals about how information is laid out or what taps are supposed to do.
What valuable preexisting knowledge is ignored if you make your button text readable instead of being blurred with the glassy background?