Because Nvidia doesn't really support the 76x series on laptops DIRECTLY (similar to a lot of their other laptop GPUs actually). They expect vendors (MSI/Clevo/Dell/Lenovo/Whoever) to come up with the drivers.

You need to mod the Nvidia driver ".inf" file if you STILL want to update. If you can't, don't bother updating unless you have a serious issue with any of the games you have.

I personally don't see THAT much improvement over stock 311 in the games I play anyway, at least not as much as actually optimising the settings for each game myself.