I can't stand how people say this.
A lot of things cannot be done with solely a mobile site. Most of the things that come to mind are media-related. (This list is tailored to iOS, because the last implementation of the app was iOS-exclusive.)
*Access the camera app or photo/video library. A native app could allow you to shoot shots or video and then upload directly to NS. iOS 6 will allow photo uploading via Safari, but only if the mobile site enables that. If not, you'll still have to tap over into the Full Site, which can be a pain. An app would be easier here.
*Access the device at all, short a few minor features. Sure, Safari has access to your location, if you allow. But you could go so much farther. In an app, you could easily connect to Facebook and Twitter for dual login or automatic/manual sharing. (For the record, I share forum posts that I make with my Twitter followers quite frequently. This integration is necessary and useful. It's a logical progression). You could link with iCloud to sync your NS login, inbox, and notifications between devices. You could access to accelerometer and "shake to view a random video." The list goes on.
*Media in general. Audio, video, and photos are just better when done natively. There's far less room for the app to crash and you don't have to worry about compatibility. Everything just works.
*Notifications, notifications, notifications. This is where a notification system for the wider NS ecosystem is going to start. I can see it. The world is moving toward mobile. NS too will move toward mobile. I would love to get iOS notifications when I receive a PM, am quoted in a post, or someone replies to my B/S/T thread. The best part is that everything could be controlled by the user, if the developer allowed. Just say what you want notifications for and what you don't. Simple.
*Live lists. You could do auto-refreshing forum post lists in an app. Not in a web browser.
The idea that "there's no need for an app; there's a mobile site" is completely flawed and frankly incorrect. While the mobile site is great for quick posts and the home page, the addition of a well-built app with a feature set near-identical to the full site is critical to the site's survival. With things like AdBlocker and mobile devices already diluting the market for ads, the Internet is turning to mobile. If Newschoolers intends to be financially sustainable in the future, they'd better get their mobile presence on lock. The best part for them is that there's no way to avoid ads in iOS. They're built into the OS!
So get on it. I thought the new parent company would remedy this issue quickly, but I was wrong. There's a lot of money to be had in mobile, and I think with a well-built app, it could create a lot of revenue for the site.