There's a lot of high-profile games either out or coming soon for Android, but even the staunchest Android evangelist (this guy!) would have trouble denying that the gaming market on iOS is more robust at the moment. The current posterboy for iOS graphics is Chair Entertainment's Infinity Blade, a hack-and slash action game with some undeniably incredible visuals. When asked when they'd bring the series to the even more popular Android platform, the devs cited fears of piracy as a reason not to create ports.
Mashable asked the two brothers who designed the game why it hasn't appeared on high-powered Tegra devices yet, and their response was that a "wild west" business environment had left the door wide open for piracy. "We’re confident that will be worked out and it will become a viable place for game developers, but that hasn’t happened yet." The developers said they were open to creating Android games in the future, but at the moment it's not part of their plans.
It's true that piracy is a problem for Android. Most apps sold in the Android Market don't have any sort of copy protection (and I'm not saying that it's necessarily a bad thing). But to develop exclusively for iOS out of a fear of piracy is a flawed argument to say the least - piracy is also a problem on iOS, and a quick Google search shows that Infinity Blade is available to any unscrupulous iPhone users who wish to take it without paying. There's a lot of good reasons not to port a game, like extra development cost for a platform that typically renders fewer direct sales. Piracy isn't necessarily one of them.
For the record: do not download commercial software without paying for it, on any platform. It's illegal just about everywhere, and you'll make Santa cry.