There are other costs, like fragmentation: not everybody agrees that "monster" is a good replacement, and there are many places where it definitely isn't a good replacement. Then there's changes to documentation, wikis, and other written documents. Not to mention time spent discussing alternatives and spreading the word.
On a personal level, it may be a few tiny tweaks but also very tiny personal impact. On a global scale, it could be a larger impact but also takes a lot more effort (combined effort of millions of tiny tweaks). Whether that effort is worth the payoff is debatable, especially considering what other initiatives that effort could be directed to.