I was witness to a debate with a couple of friends a few days ago on the issue of taqlid  and following a particular madhab . One of them was duly observant of adhereing to a particular school (Hanafi in this case); the other, though respectful of particular opinions, saw no reason to restrict oneself unduly (he was what I would describe as Ahl-e-Hadith).
This conversation -- strangely a calm affair, and without the usual mud-flinging -- had me thinking. I would like to break one side (the Traditionalist) of the argument down. I believe it runs like this:
1. An individual Muslim (the "lay" Muslim) cannot determine, for himself, what is and isn't "Islam" (in this case, what is and isn't 'legal'; or what is and isn't halal or haram etc., as well as all the other classifications regarding obligations, duties and so on).
2. For this he needs to ask a specialist (a scholar of an Islamic discipline, usually someone trained in law), i.e. someone who is qualified to give an opinion.
3. But he must ask the "correct" specialist.
4. The individual Muslim, must, therefore, determine who is and who isn't a "correct" specialist.
5. A "correct" specialist can only be a someone from who is trained in one (or more) of the four schools (of classical Islam), and also adheres to a particular school (i.e. practices what he preaches).
6. Since the "lay" Muslim is not qualified to make a judgment on the 'fact of the matter' (that is, analyse a "text" for himself), he is not allowed to base his judgement of who is and who isn't a "correct " specialist on the argument in hand (that is the particular opinion).
7. So his judgement must rest solely on recognising the correct "authority".
8. Therefore, what is important in taqlid (from the point of the "lay" Muslim) is not the actual "content", but the "authority" of the opinion.
A "lay" Muslim who champions the Traditionalist view can criticise an interpretation which is not from "the four schools" (who, for the sake of this argument, we will call a "Modernist" -- though I don't usually ascribe to the tradition-modernity duality). But then in doing so, he violates the very principle (outlined in 6) which he claims to adhere to. The only reasonable response from the "lay" Traditionalist could be that he does not recognise the Modernist scholar as an "authority". Certainly, the lay Traditionalist can criticise the Modernist that he has no "credentials", i.e. has no "recognition" amongst people he believes are the "correct" specialists. But for him to move into the debate and begin to inspect the actual opinion of the Modernist scholar seems like a violation of his own principle.
I would also reiterate my comment (8): taqlid seems to have nothing to do with content, at least in the first instance; content is subsumed under authority, because authority determines what is and isn't "content" for the layman. In other words, a Modernist scholar, in the eyes of the lay Traditionalist, must be "wrong" not due to the content of his opinions, but due to the lack of his authority.
The problem, however, isn't one of taqlid, which often receives a bashing from various Modernist and "Progressive" corners. We all recognise "authorities"; when working in a certain discipline, we must adhere to the rules which have been laid down by a variety of "authorities" (although these rules can be, and are, subject to change -- if only subtly). And certainly, if we haven't learnt the rules, we cannot play the game. Further, there are, as I understand it, levels of taqlid starting from the relationship between the layman and the scholar, and then between a scholar and his teacher, and so on. Sloppy use of the term (much like the use of the term ijtihad) doesn't really benefit anyone.
Indeed, the Modernist would do well to be careful what he does say regarding taqlid -- for ultimately he must also recognise the "authority" of the Prophet (p). There are also associated devices (scholarly lineage, chains of authority etc.) to consider.
The real problem (given that people accept there is one) seems to come back to a more fundamental issue: what exactly is the purpose of the Law?
 Which means something like 'covering with authority'.
 Usually taken to mean 'school of law'. I also refer the reader to a defence of following a particular madhab.