as a graphic designer, would an application icon need to be updated to match the simplicity and flat UI of iOS 7? Do you think this would contribute to the UX overall?
I think it depends how your icons looks currently; if it doesn't fit new guidelines then Yes it's worth changing. Users's impression of your icon is important.
Here are the icon guidelines for iOS7 Apple HIG – App Icon
iOS7 app icon guidelines
- For the best results, enlist the help of a professional graphic designer.
- Use universal imagery that people will easily recognize.
- Embrace simplicity.
- Create an abstract interpretation of your app’s main idea.
- If you want to portray real substances, do it accurately.
- Make sure the app icon looks good on a variety of backgrounds.
- Avoid transparency.
- Don’t use iOS interface elements in your artwork.
- Don’t use replicas of Apple hardware products in your artwork.
- Don’t reuse iOS app icons in your interface.
- Create different sizes of the app icon for different devices.
- Create a large version of your app icon for display in the App Store.
This isn't as easy an answer as it may seem. Whatever you do, many (if not most) apps will take a while to update their icons to a flat style.
So if you update yours early on, your icon will be the lone flat one among many glossy ones, thus looking somewhat out of place. However, if you don't update your icon, it will look outdated as other apps start updating theirs.
Overall I would err on the side of creating an appropriately styled icon sooner rather than later. That way when you stand out initially, at least you are standing out as an app that is cared for and updated regularly.
TL;DR: Yes, but not that critical initially
An interesting article on The Next Web touched on iOS iconography, and how critical it is to the user experience:
The result is a strikingly different, if divisive, take on a new set of iconography for iOS 7. Though the designs of the apps are also very important, the icons are iOS 7’s first impression and calling card. That’s why it was important to have them trend downward in age and upwards in vibrance.
The overall gist of the article is that Apple is making a very large break with the past by creating an entirely "new" design language. The iconography is one of the most immediate statements an app can make to the user.
Having an application speak the same language as the environment it runs in is important not only because it makes the interactions discoverable by presenting familiar visual cues to hint at functionality.
Having an application speak the current language speaks to the quality or trustworthiness of the application.
One could not update anything about a iOS application from a user interface perspective and the user will still know how to use it because they are already fluent in the old language.
But your app will be saying to the user that it is old and its makers don't care enough about it to keep it current. That will make the user uneasy about trusting that the app will be reliable or will work in the future.
So for these reasons, I think that the effort involved with updating your app's icon is worth it and will result in a better user experience.
iOS 7 app icons are larger than for previous Retina versions of iOS, so at the very least you should provide an icon at the new 120 x 120 size.
Glossy icons look out-of-place with the flat icons, breaking the consistency and hence UX.
Yes, icons more in line with the devices style make the app look more complete, polished and professional. It is simply better graphic design, which is part of the experience.
But Apple hasn't yet finalized it's new icon style. The icons in the current iOS 7 release are clearly inconsistant and work-in-progress. There are varying degrees of "flatness" exhibited. I'd wait til the new icon style becomes more solidified before reworking your icons.