Consequences of allowing packages to quiz users at install time
I suspect that one consequence of allowing packages to ask users questions at install time, as Debian does, is that it allows divisive packaging issues to stay unresolved because people can always say 'fine, we'll offer both options and let the user choose'. No one actually has to compromise or give in, so everyone sits around quietly nursing the issue until (if you are lucky) it all gets forgotten about.
(Of course, then you can have a new flamewar over what the default choice should be.)
This in a sense seems perfectly suited to how Debian seems to do things, since from what I have read Debian does not strike me as a place where there are strong authority figures who can make decisions and make them stick. It's possible that the ability to defer making completely final decisions on divisive issues is quite important in Debian's environment. (However, at this point I am speculating wildly, since I have no more insight into how Debian really works than reading Planet Debian off and on.)
As a sysadmin, I get to worry about another consequence of allowing packages to quiz users: there is less pressure to make the defaults sensible and useful, because you can always blame your users for not picking the right option when you asked them. In turn, this makes me nervous about turning on various Debian (and Ubuntu) 'never ask me any questions' options, because I can never be entirely sure that I won't be skipping a question that I really need to actually answer.