Exactly , there was this much expectation on the Spanish team this world cup, And this amounted pressure on the entire players.
But on before the world cup, the Spanish team is not what they used to be before, there was a drop as regards to their performance, so what makes it to become a headline and a big defeat was the fact that people was not expecting a team like Morocco to send them packing.
That is what makes football so entertaining to watch. An unexpected team defeating a team that everyone expects to win a match. Spain had played their best till that point. They were able to keep Morocco at bay until penalties, despite having the majority of scoring chances in that game. To me, penalties do not assess a team's perfection, thus their exit was just unlucky for them, whereas Morocco benefited from the penalty that day.
It's true that as you said, the unseeded team can beat the seeded team, Spain was eliminated by Morocco, while the Brazilian national team was surprisingly defeated by the Croatian national team. It is indeed very difficult to make predictions in this year's world cup, because the seeded teams must return home one by one, most likely Morocco will surprise again and be able to beat Portugal tonight, most likely Morocco and Croatia will advance to the world cup final this year this, because they have a very solid defense at the back and they also have a strong team with extraordinary cohesiveness.