I'll admit that it's a bit more work to have CMake be installed before being able to build Anope. However, as far as I can tell, no one on the Anope team (myself included) knows Autotools well enough to have it be up to the tasks that CMake was able to accomplish with how I've set it up.
My personal opinion is that the move to CMake is worth it, as having it installed is really the only extra requirement for the users, and it is a huge help on the developers. For the user side, they only really need to run Config which acts as a wrapper to CMake, just like it used to be a wrapper to configure. For the developers, the added benefits include ease of cross-platform support for both *nix and Windows, and automatic header file dependency calculation. For both users and developers, using CMake allows for both in-source building (as it was already) or out-of-source building (a separate directory to build in without cluttering up the source directory with the built files).
I'll also point out that I have used Autotools in the past. I found it hard to accomplish things with it. I've only been using CMake for a week but I was able to make the build system under it be pretty close to the Autotools system that was in use before. And this was even though I'd never used CMake before and even though I was having problems in certain areas that I was able to figure out and work with.
That all having been said, if anyone feel they are competent enough with Autotools to be able to create a build system using it that can be comparable to the CMake solution I have come up with and could possibly run alongside CMake existing, I invite someone to do so.