This sounds nice, but what about supporting operating systems besides for Linux and MacOS? A big part of using continuous integration is being able to test your code on the various platforms you deploy on. People have been asking for FreeBSD support since 2014[1] and Windows support since 2011[2]. For lots of projects not having Windows or FreeBSD support makes Travis CI not even an option for a CI tool. And from the…
Another way to look at this is that it has created an opening for competitors to fill that gap, especially appveyor, circleci, and codeship. That TravisCI is still the market leader in the cloud CI space suggests that they're making the right call by letting others pick up the more niche parts of the market.
Windows is one third of the server market and over 90% of the desktop market. Calling Windows a niche is simply wrong.