The Siri remote on the new Apple TV is fantastic for scrolling through a UI and playing a new class of games thanks to the built-in gyroscope and touch pad but it's lousy for text entry.
But the new Apple TV hardware remote is no keyboard replacement. In fact, it's a step backwards from the last-generation Apple TV. With the previous Apple TV, you could use your iOS device's keyboard to enter text via the IOS Remote App. If a text field appeared, just open the Remote app and use the on-screen keyboard.
To enter text on this Apple TV, you have to manually enter each character with the hardware remote like a dog. Curiously, the new Apple TV doesn't support the Remote app at all and other than for the initial setup process, Apple TV has no use for your iPhone or iPad. Surely though, you could pair a Bluetooth keyboard? Nope.
For more about the frustrations in these early days of Apple TV 2015, take a look at Jason Snell's piece for Macworld.
At 5 days after launch and more than a month of using the Dev kit, my best guess is a conscious decision by Apple to limit text entry on the new device. Remember that the new Apple TV is running a custom version of iOS 9.0. Devs were encouraged to port games and the process was relatively straight forward. Other apps like Speed Test and Plex have arrived on the App Store too. But what about Twitter, Pages, or Things?
Apple has made it nearly impossible to create or port apps that require more text entry than a basic search term or password. I mention Pages because it is technologically possible for the Apple TV's A8 SoC to run the iOS version of Pages. The market should decide if Text Editors on Apple TV is a good idea, not Apple.
Either Apple doesn't feel text editors have a place in the living room or decent text entry is an afterthought. I would believe the latter, that maybe it's coming in a future software update, if the Remote had never existed and we had not been able to pair a Bluetooth keyboard in the past. It's not a misstep, in tvOS it's by design. Things may change in tvOS 2 but I'm not holding my breath.