I have reviewed or maintained the code of tens of other programmers and came out with your same conclusion. Writing code like that is acceptable if you know exactly what your users want, and you won't need to build any features on top of it.
Right. It seems to me that most coding "best practices" are designed to help you maintain and build on your code. The guy who hacked together the animations would be in a world of hurt if his boss came in and said "we need the pool of blood to empty in case A, and in case B, it needs to be water, and in case C, it needs to be a cuddly bunny instead of a skull. Also the animation speed should vary depending on the time of day." This would be even worse if 6 months had passed since the original code was written.
Suddenly, refactoring for flexibility and clarity would sound really, really smart.
Now, if I'm writing a piece of "throwaway" code - say, a script that I'm going to run once to accomplish something, then never use again - I'd agree with "do what works and don't worry how the code looks." But generally, if your code matters to anyone at all, it will need to be tweaked and maintained.