It's been brought up in this thread a few times, but my bigger nuisance is around the multiple user topic. YES I understand it was never Apple's intent for people to store more than 1 user's fingerprint and YES I know you can always opt to use the passcode etc. but the reality is some people like enabling multiple users.
My wife and I store one of each other's finger prints on our respective phones. Again this is strictly for convenience as we know each other's passcodes as well. I'm sure this post will be met with the above arguments or comments about how we shouldn't be on each other's phones etc. but we have no issue. Often time we have to access each other's phones (i.e. when one of us might be driving). However even apart from the multiple users on the phone, I think this would be a bigger nuisance on our iPad.
We share a single iPad in our household. We are not power users, but use it for basic things like browsing the net, responding to emails etc. We keep it on our coffee table and both freely use it as needed. Again I am preempting the arguments about not using it as intended or to use the passcode etc. I get that. Again speaking purely from a convenience and universal user experience perspective, it would be a nuisance if multiple users could not be supported. Just my thoughts given our use case.