Lack of features isn't what's stopping AppleTV from selling a gazillion models right now. There's just not enough buzz about it. They're still getting started - compare it to, say, video iPods. Most people said they had no need of one, and many still don't have it. But eventually they became the thing to have, and they're selling in very, very comfortable numbers right now.
Since Apple (wisely) never gave a target for early sales, I'm not even sure what number would be good or bad at this point. 10,000? 15,000? Apple clearly don't expect iPod-like figures; for one thing, it's a one-per-household item, and kids won't be running out to replace them with every revision.