In the bug report # 285966 (avoid inheriting transparency when it's set to 0) I commented about the problems of the style inheritance in new shapes. New users seem to be very confused by this feature, and in the particular case of creating a shape after setting a gradient (the style of the last stop is preserved, so the last style memorized is A=0) it leads to recurring bug reports because people don't get it and tend to think that there's something broken. I've been thinking about the inheritance of opacity and honestly, I find it rather annoying in most of the cases.
At the moment is marked as a wishlist item, but I'm starting to think that it's probably an usability bug.
I think that should be better to avoid opacity inheritance as default and make it optional via preferences (i.e.: preserving fill and stroke but not opacity unless the user select the proper option in the prefs).
What do you think?