To be fair, it was reasonable to expect something big given the last Pokemon Direct announced Gen 6, was even shorter, and had full gameplay. I don't condone the complaining but telling people to shut up and be grateful isn't exactly that helpful.
I do get what your saying. It was obvious that these new games were suppose to have been a surprise like the announcement of the direct was. But, the fact of the matter is we knew a new game was coming though. If anything we just wanted a confirmation of that new game and yet people are upset as to how it was presented through the direct, but not upset as to how it got leaked online. The thing that I'm mostly upset about is you can't blame the company, it wasn't their fault, you can't stop a leak, whether you like it or not.