This is kind of saddening to see, but it is a crime that virtually every programmer has committed at one point or another in their careers. Let's be honest - in some cases it can be quite fun to do. The underlying problem is the ego, and the corresponding lack of objectivity that results.
From reading someone else's code - even glancing at it in some cases - one can infer a great many things. For example, if the indentation on some code is totally borked, most programmers will immediately be extremely doubtful about whether that code contains any interesting or useful ideas (though of course this is not always the case, counterexample being intentionally obfuscated code). In some cases, they will simply refuse to continue attempting to understand the code and dismiss it as useless. A similar thing can happen at the semantic level when the programmer detects a mismatch between the language/framework being used and the problem space; this dissonance is likely what is irking all of the people who are so childishly ridiculing your replace utility.
Sometimes when you're looking over someone else's code you spot some perceived inconsistencies/flaws/bugs. The crucially important part is what you do next. If you choose the route of publicly shaming them to stroke your own ego, then you have not only hurt yourself by appearing childish, insecure and unsociable, but you have also hurt their feelings. It's important to remain objective in these situations, and take the self out of the equation. If you HAVE to indulge yourself by tearing the code apart in a humorous manner then at least keep it between with your friends!
As I alluded before, I would guess that the reason people where poking fun at it was probably because there exist a lot of other utilities which have the same functionality and are readily available on most any system. Personally, I thought your code was interesting, and I thank you for choosing to make it public :).