I can't completely tell if it's the microswitch being stiffer or the button itself (slightly stronger spring?). Hard to tell
Take the button spring out completely and then try it. If the buttons are the type where the plunger leg is in close proximity of the switch actuator nub, the plunger should still sit high enough. This will remove the plunger spring from the equation, and lower the overall resistance. 75g is way too stiff for good button action, unless you are a "basher", but it should be plenty for the plunger to return without a spring in the button.
As for keyboard switches being the "best" choice for arcade buttons, I consider that a matter of opinion (at best) and they
must, of course, have a spring mechanism of some nature inside to return the actuating part.
