From what I've seen is it depends on what type you get, and the quality... Molten Pro-Touch Men's and Women's are nearly the same, but are rather good quality. They are "firm", not hard... And they work in nicely
The club I run has some older, crappier balls - that brand new - or broken in are always horrible quality. We have a "medium" grad ball that we ordered, it was soft to begin with, and only got softer with time.
It usually depends on the type of ball you get (indoor, outdoor), the quality - and over time many do get softer.