I'm not sure if I get your point. When you say "this system", do you refer to exactly this system or this kind of systems?
If you mean that there already are a lot of creep respawn systems, then my answer is simple: There are none at wc3campaigns -> Resources -> Systems.
If you mean that my system isn't useful, then that would be a subjective opinion. I have myself implemented this in a map of mine, and the creation of many respawning creeps have never been easier. Have you actually looked at the code?