There is a line between "story" research and "useful" research. All research will tick the latter category.
Suddenly, finding out the origin of the virus is very important. It goes into finding a weakness, and unlocking weapons and abilities that cater to that zombie type.
While finding weaknesses is kind of a cool part of the "story" if this game is really short, it's more about speedy replay for me.
I don't want to have to scroll through the same 4 stories (which I'm sure could be compelling) when I've played 8 or 9 times and I know the different strategies. And how much more work goes into different stories when the zombies are still headshot = kill (generally)? And I'm not coding the game, but I'd guess there could be balance issues too trying to make less common items more common for one strategy or the next.
But regardless, thanks for the great games, keep up the great work.