With this patch, Matt is inherently indicating that, with respect to the capitalization of "WordPress", end users of WordPress do not, in fact, have the right to use the application according to their own purposes as end users. Users can no longer (intentionally or unintentionally) mis-capitalize "WordPress", without extending core to remove the filter.

I find this inherent indication fascinating, given the fanatical, dogmatic pursuit of software freedom in almost all of Matt's (and Automattic's, and the WordPress project's) words and actions.

This statement is part of GNU's definition of "free software":

"The freedom to run the program means the freedom for any kind of person or
organization to use it on any kind of computer system, for any kind of overall
job and purpose, without being required to communicate about it with the
developer or any other specific entity. In this freedom, it is the user's
purpose that matters, not the developer's purpose; you as a user are free to
run the program for your purposes, and if you distribute it to someone else,
she is then free to run it for her purposes, but you are not entitled to
impose your purposes on her."
Reiterating:

"it is the user's purpose that matters, not the developer's purpose"

According to the definition and philosophy of free software, Matt and his pedantic desire for "WordPress" not to be mis-capitalized can go pound sand. His desire is completely and entirely irrelevant to the end users' purposes for WordPress.

This function provides absolutely no benefit to the user community of WordPress. It is the epitome of pedantry. If I'm wrong - if such a burning need and desire for such a filter exists within the community - then move the entire function into a plugin, add it to the repository, and see how popular it becomes.

It is not so much the bad decision to add the function to core that bothers me, per se; bad decisions are correctable. Rather, what concerns me is the attitude and response of the core development team (primarily, Matt himself) to the criticism from the community for making the decision:

The function inherently makes editorial changes to user content without user knowledge or consent? Who cares. WordPress must be capitalized correctly, at all costs!
The function breaks user content? Who cares. It works on wordpress.com. The damage has been done, and fixed. Everything else is just an edge case.
The function adds unnecessary overhead to core? Who cares. It separates WordPress from all of the other soulless (and, presumably, less pedantic) CMS alternatives.
The function is no more useful than many other functions and patches that have been rejected from core due to their trivial nature and niche use? Who cares. Matt wrote it.
The function is terribly unpopular, as evidenced by the wp-hackers mail list, the wordpress.org support forums, and the overwhelming "+1 revert" comments on the Trac bug report related to the function? Who cares. Matt discussed it with the core devs before he committed it. It's not really a "vast majority" who are opposed; just a "vocal" minority. And if you don't like it, vote with your feet, or write a plugin to remove the filter.

None of the above are responses that give me much confidence in the core development team's respect of, concern for, or commitment to the WordPress user community.