We can thank the devteam/jailbreakers that enabled native apps on the iPhone.
Prior to that, when Steve Jobs gave birth to the iPhone in 2007, it was only meant to run Web-Apps. Because of the large interest of the dev community of wanting to code and run native apps and creating a custom tool-chain, Apple then released iPhone SDK 1.0 a year after along with AppStore.
Also, when the first Intel Macs came out, Steve said we are not allowing any other OSes other than Mac OSX to be installed on our Macs. But many people demanded Windows to be run os the iMac including business people. Months later, two hackers managed to create an EFI boot loader and booted to Windows XP. Critics said it was fake while others believed. Soon after that, Apple annouced Bootcamp as a public beta as a means to dual boot to Windows on Intel Macs.
I am not surprised if Apple released AppStore for the AppleTV's soon to be gaining popularity. The only thing that matters is when and "When the time is right."