I don't have too much a problem with the hardware grade, as I'm sure they've already done the math to make sure the bolt strength is sufficient for the installation. But I agree, for the customer peace of mind, it couldn't hurt, but it's probably not necessary and would add to the final cost.
The other thing I'd have liked to see is some loc-tite included in the kit. Again, it's probably not necessary since the kit includes lock washers, but I put blue loc-tite on all the fasteners just as another backup against the fasteners coming out. If I really didn't want the fasteners coming apart, I'd torque everything and put a tack weld between the bolt threads and the nut surface. But where do you draw the line? If I wanted to go all out, I'd use hot steel rivets and a big dog air hammer. But the cost/benefit ratio just doesn't support it.
While we're on the subject of installation, I'm planning on using the non-strut style A-arm lower control arms with air bags. Can anybody come up with a good reason to install the strut rod brackets if the strut rods aren't going to be used?