It is open source, and it's commercial. It's both. The word "Upgrade" is right there at the top of the page. It's not in the last surprising, or hidden, and thousands of businesses here promote themselves with a freemium product.

That doesn't detract from the generosity of giving something away - the only reason it's not been forked and improved by others (for free) is that nobody blinkin' wants to without payment.

Just take what's free, or pay for what's not! I don't know why that's depressing at all.