It's an issue of sales volume and connector standards. iStuff is made to use the same connector, which is designed with accessories in mind, for multiple generations of products that sell at higher volumes than other devices. So as accessory manufacturers are looking at making stuff, they are considering how many they can sell.
As of August:
From what I can find, about 3 million Nexus 7s have been sold. So comparatively, the market for iStuff accessories is HUGE. On top of that, because Android devices don't have a standard for docks, accessories are only relevant as long as the device they are specifically for is relevant. For tablets, that's what... 9 months? A year? Meanwhile iStuff docks have changed only once since launch that I'm aware of, and you can still use a lot of older accessories with an adapter.
I too would like more accessories, but you can't expect anywhere near the same variety as is available for iStuff unless a standard is created for Android devices, which I don't see happening.
Facebook
Twitter
Instagram