When you first visit the TinyMCE website and check out the examples, you see a very advanced editor, in terms of the share number of functions. But as with most software, the real power is what is behind that graphical interface, the structure and quality of the code, the way it can be configured.
The challenge as a developer is not to build yourself into a corner, don’t follow a path that ultimately will lead you to producing bad or bloated code. On the last rewrite of TinyMCE a lot of thought was put into how to avoid problems like that, and I think we did an excellent job, the code base feels very solid.
One example of powerful configuration is the valid_elements and extended_valid_elements options in TinyMCE, where Spocke invented its own format that has now spread to other projects, read more about the format on the documentation page.
The same goes for our other products, MCImageManager and MCFileManager, there is so much stuff going on behind the scenes in these products its crazy, we even implemented a form of .htaccess type configuration override (but we call the files mc_access). Means that most of the options you can set in the config.php file, you can also put into mc_access files to control the configuration for different folders. For example, you could make it so that if you upload a file to a certain folder, it re-sizes those images to a fixed small size, but if you upload to a different folder, you get a big image. You can restrict access to even upload, or disable certain functions in certain folders, and much much more.
So, check the documentation, even if you are satisfied with how it works, perhaps you can find some hidden gems that are extra useful just for you.