Re: "Intellectual property exists to encourage innovation"
"I'm currently working on some language learning software, but I can't [patent] my ideas"
Sure you can: patent a method of learning a language. That it can be implemented in software should be incidental. If the method cannot stand on its own merits then so-be-it.
"It encourages ground-up innovation [...] but in some ways it does discourage *incremental* innovation"
Don't flatter yourself. It's *all* incremental innovation (you've just not performed a patent search yet).