It all depends on how that one percent is computed.
You are correct that if you take 75 and add 1 percent you get 75.075. Not much improvement there.
However, if you consider that your chance for hiding success is somehow related to (75 skill) divided by (250 max skill), then you have a base 30% chance of hiding. Add 1% to that and you get 31%. Better. One percent in this case is actually a 3 percent increase.