Well it is hard to answer precisely, but I will give my opinion: The study of the Gauss-Kuzmin problem eventually led to a fruitful connection between continued fractions and functional analysis. Namely, the distribution function of the Gauss measure is the leading eigenfunction for the transfer operator associated to the Gauus transformation. It turns out that this is the hidden explanation for the theorem you quoted in your question.

Understanding this connection recently led to a detailed study of transfer operators of the Gauss map and related transformations, and their associated Dirichlet series, which paved the way for major breakthroughs by Baladi, Vallee, and others, in understanding the statistics of the Euclidean algorithm and its various analogues. It would be difficult to give more details than this without writing a very long post, but if you are interested in finding out more then here are two references:

1) "Euclidean algorithms are Gaussian", Baladi and Vallee, available on Viviane Baladi's webpage.

2) "Continued fractions", Doug Hensley, Chapter 9.