Because people like to find type errors at compile time, not runtime, they want to know which types a function uses, and they like to have usable code intelligence in their IDEs (code completion, find usages, rename symbol, etc.). VSCode with Pyrite is the best option I've found for this. It makes Python feel less like stabbing in the dark.

The fact that you like Python for being "runnable pseudocode" suggests to me that you only use it for very small scripts, in which case it is true you don't really need static types or type hints. But many people use Python for much larger programs and in that case it is really indispensable.