"[A]re there any psychologists out there who can save me the bother of having to work out 'why it's better to pretend you're a libertarian'?"Rather than being one, I almost certainly need one - although I console myself in the knowledge that most psychologists and psychiatrists are in greater need than me. I digress - I'll attempt to answer the question - or at least make a couple of suggestions.
Implicit in Paulie's question is the idea that many self-styled 'libertarians' are, in fact, anything but. If I've understood him correctly, I think he's right about this. The question might be more accurately put, not why is it better but why is it easier to proclaim oneself to be a 'libertarian'?
1) Part of the reason is down to what both Isaiah Berlin and Maurice Cranston identified - liberty or freedom are 'hurrah' words; concepts that people automatically want their ideas to be associated with because of their positive connotations. There is a good and simple reason for this, which is that human liberty is indeed a good thing. Or so I would argue. Consequently those who really favour limiting human freedom prefer to call it something else. Few people have the courage to admit they favour less liberty in order that some other human good may arise - which brings us to the second point.
2) There's either a refusal to admit, or a lack of courage to acknowledge, that human values collide and cannot be fitted into a harmonious pattern where everyone will be happy. It's a reluctance to admit, in other words, that trade-offs have to be made. For example, those who favour restrictions on the use of narcotics would be today much more likely to say they favour prohibition in order to save people from the slavery of drug addiction, rather than frankly admitting that they believe this area of human activity should be restricted in order that other human goods, such as health and welfare, can be enjoyed. In other words, people feel the need to dress up their chosen authoritarianism - and we all have them - as 'real' liberty.
To illustrate the point one has only to look at the abortion 'debate'. Protagonists on both sides shriek their absolutist positions using the language of 'choice' and 'rights'. My own view is that it would be better if people like myself who favour some more legal restrictions on a women's right to choose a termination should honestly say they favour a more illiberal policy in order that some other good may result, without dressing this up in spurious language about 'rights'.