androidDespite the explosive growth of Android, application developers have voiced their share of complaints about the platform. Eric Chu, group manager of Android, tried to address some of those concerns today while speaking to an audience of developers at the Inside Social Apps InFocus conference in San Francisco.

Most specifically, he talked about the rejection of “mobile arcade application” Kongregate from the Google Android Marketplace.

“It’s clear within our terms of services that you should not distribute a competing marketplace or store,” Chu said. Applications that sell physical products or virtual goods are fine, but competing app stores are not. And Kongregate, in Google’s eyes, was clearly an app store. (I’m pretty sure Chu wasn’t commenting on the fact that Kongregate was just added to the Marketplace again. With the new app, in an attempt to get around Google’s restriction, games aren’t downloaded onto the phone.)

That seems like an interesting statement coming from Google, which is constantly touting its openness, especially when comparing Android to Apple’s App Store. But Chu said it’s important to distinguish between Android as a platform, which is totally open, and Google’s Android Marketplace, which Google needs to control more tightly, so that apps deliver a good user experience across multiple devices. If developers don’t like the Marketplace’s restrictions, that’s why there are a number of other Android app stores.

“Competition is always good,” Chu said.

Another big topic during the panel was the Marketplace’s lack of support for in-app payments, which has been cited as one of the reasons that Android app developers aren’t making as much money as their counterparts on the iPhone. Chu said his team is working hard to add that feature as soon as possible. In the meantime, he said Google doesn’t want developers using other in-app payments options in the Marketplace — because again, it wants to protect that user experience.