It did not come as a surprise and it is not rationalisation in hindsight to claim that it was to be expected.
Pandemics do happen, we know that and we experienced several ones in the past century, and it was expected that a serious one would occur with very serious consequences. In fact experts have been repeating that for decades.
Not only that but it seems that this pandemic followed the most likely scenario according to experts, i.e. a new virus jumping from animal to humans. Even the likely animal candidate (bats) was near the top of the list (we already recently got SARS, probably MERS, and perhaps Ebola from them).
It is a shame that those in power have the ability to discount the scientific community who were saying for years that something like this would happen. I mean look at SARS & H5N1.
Hopefully the world will be better prepared for the next one. At least until the current generation or two retire and its no longer in the collective memory(Like the 1918 Spanish flu)