I'm actually not as concerned about outright knockoffs - I'm more concerned about intentional confusion, other Chinese learning products (not even necessarily dictionaries - courses and such) trying to make people think they're developed by Pleco. We have in fact had numerous companies (including some fairly big ones in the space) try that - had one on iOS that even inserted a 魚 in their icons to make them look like they were affiliated with Pleco.
And I'd have to disagree with that "very few apps" comment - a quick scan through the Google Play Top Free charts suggests that roughly 50% of top Android apps use icons that are either pixel-for-pixel identical with their iOS equivalents or differ only in their corner shapes. Your app icon is your brand, more-or-less - the average user is far more likely to recognize our icon than our swimming fish logo - and consistency on that front matters; look at Instagram, that icon (while beautiful) really only "fit" on pre-Retina-display, pre-iOS-7 iPhones, yet they've stuck with it both on iOS 7 and on Android because it's so recognizable.
Anyway, as I said you can easily swap in an alternate icon if it bothers you personally, as can anyone else, but for the place our app icon actually matters most - app store catalog listings - I think the arguments in favor of keeping the iOS 7 design are quite strong. We may consider adjusting that design at some point - picking a different color, say - but we'd want to do it in a way that could remain consistent between both platforms, so I still don't think we'd make it particularly Material-ish.