Why upgrade at all?

Playing devil's advocate - we've been using CI 2.0.1 since 2012 and are happy with its functionality and performance.  Other than end-of-life issues for CI 2, what advantages / new features would we see by upgrading to CI 3?  As far as we can determine, CI 2 is not broken, and there is no need to fix it.

We have approximately 58,000 lines of code in our application directory, if that has any bearing on recommendations.

Thanks,
Dorsey