@Leadfoot,
Honestly yes it does make me wonder, I have a big problem with the word "Randomness" when it comes to absolutes...nevertheless natural selection happens. Now if you want a tinfoil hat theory on that I would point out a couple of things:
1 - We don't know if it did happen before mankind is very young around 150-200 thousand years old.
2 - Extremely deadly viruses tend to go extinct very quickly as the more they are efficient at killing their host population the faster they go out of the genetic pool...
3 - Life exists on Earth for 2.5 to 3.8 Billion years ago (Farmerman correct me if I got this slightly wrong on the numbers here) Plenty of time for Nature to play with super deadly "bugs" and send them out of the genetical pool way before big fauna has arisen...
Still, you can argue that given the extreme rate of mutation of viruses and the super-fast cycle of Evolution they have along with the huge variety of specimens it should be happening all too often if the mutations are truly random. To this, I have no good explanation and that was why from the start I conceded that it does make me wonder.
Since I am not an expert on the subject, not even an amateur, I would like to have input from people like Famerman and others that might have a better explanation than the one I got. I like to hear from a varied nonbiased set of diverse opinions.