Presumably because Go is hip, new, favoured by people on HN for some reason, etc. ?
The attitude that once a new language comes out we need to drop all the old ones is not very helpful. Python is used by many, many people (more than Go, I'd venture) and having it available in something like this instead of having to work with Arduino and others which can be less user-friendly is spectacular.
I'm a python developer myself. I just started with Go. I'm just saying that Go fits microcontrollers better. Its cool to use Python. It doesn't matter much.
I'm just saying that cool would also have been a good fit.
Actually you said "much better suitable for these microcontrollers" which you haven't explained yet. I think that's why you're getting these comments. I don't use GO, and think the Rasberry Pi is better than this thing anyway.