Yes, your first example of RegEX text replace function is a clear example. But all other examples fall under the same function. (bb code tags replace, delete specific texts in many pages, etc)
It seems to me that you need only this, while wikipedia has a large number of bots.
A bot is a script that not only does something once, but often keeps on performing the same task. For example, you could have a bot that runs once per week to change all instances of X to Y.
I think the concept is interesting.