Earlier quoted context omitted.
This is a personal view but I think there is. I think that AV could make the process of voting different/confusing enough for many voters to be turned off of voting or, perhaps, screwing up their ballots. If I agree with only one element of the "No" campaign, it's that enough of the electorate is stupid/ignorant enough to find the change difficult changing the outcome of future elections.
This probably sounds terrible, but if you are too "stupid/ignorant" to write your preferences in order 1-5, are you really competent enough to be voting? I really don't expect there are many people (or any, I mean, really?) who are that stupid - that's just doesn't seem a valid reason to be against it. If you just write "1" instead of an "X", it's exactly as easy as the current system. Could you do it? Can you really…
Assuming that everyone's an intellectual and will research and consider the options and then make an informed choice is both idealistic and unrealistic. Many people have better things to do with their lives than thinking about politics and they're out there doing them. Making the voting process even more complicated is hardly going to compel them to get involved.