Writing about why Colombia might want to sign an FTA with the U.S., Phil Levy -- responding to a blog post by Clyde Prestowitz -- says:
... it may seem a bit odd that a country like Colombia would devote so much time and effort to negotiating the agreement and seeking its passage without even bothering to assess the country's current market access terms. And yet, how else can we explain their behavior? What could they be thinking?
One radical approach would be to ask. A couple years back I did just that in the wake of the implementation of the U.S. FTA with Peru. There are important differences between Peru and Colombia, of course, but both enjoyed substantial access to the U.S. market under the same preference programs (Andean trade preferences). I conducted a series of interviews in Lima with those who were instrumental in negotiating the agreement, with academics, and with leaders in key sectors such as pharmaceuticals and textiles.
As one might suspect, they were fully aware of U.S. preference programs and the rules governing market access. However, they had observed that the programs were being renewed for shorter and shorter time periods. They feared that one day, in the midst of Congressional squabbling, the preference programs might be allowed to lapse. They were prescient: in February of this year, Andean trade preferences did lapse. Peru's access is secure. Colombia is left out in the cold. (USTR Kirk and Secretary of State Clinton issued a call yesterday for a reauthorization of these preference programs. Whether and when that will happen will depend on the broader untangling of the trade agenda impasse).
A far more important lesson of the study, though, was that concerns about U.S. tariff levels were not the principal driving force behind Peru's push for an FTA with the United States. The Peruvians were focused on attracting investment. Tariffs played a role, of course; uncertain market access served as a deterrent to investment. But issues such as investment policies, services market regulation, rule of law, and signals about Peru's commitment to economic reforms were given much greater weight. The FTA was a way for Peru to sign up to an internationally recognized set of standards for commercial behavior. As such, it paved the way for Peru to negotiate a quick series of bilateral deals with other countries in its aftermath.
...
In Prestowitz' defense, even distinguished trade analysts have fallen prey to the temptation to overemphasize the role of tariffs and market access in North-South FTAs. For example, this is the basis of Jagdish Bhagwati's attack on preferential agreements as "Termites in the Trading System." For academic trade economists, it is the equivalent of looking for lost keys under the lamppost - that's where the light is. We have good tools for analyzing tariff reductions, very few for analyzing a bolstering of the rule of law. Academic journals can favor rigor over relevance.
I've often wondered why I could not find much analysis of the economic impact of trade agreement provisions other than tariff/quota reductions. I'm not an economist, so I thought perhaps I wasn't looking in the right places. But Phil Levy knows where to look, and he can't seem to find anything either.
So why isn't there more analysis of provisions dealing with issues such as regulatory expropriation, the rule of law, or intellectual property protection? Levy suggests it is the lack of tools for this analysis, which is certainly a possiblity. But it may also be that some economists do not see much benefit to international rules of this sort, and instead consider them to be negatives that have to be accepted in order to get agreement on the positives that result from tariff/quota reductions. For example, see p. 279 of this link for Bhagwati's negative take on TRIPS, and p. 313 for his criticism of the Multilateral Agreement on Investment. So perhaps the answer is that they support trade agreements generally, and don't want to draw too much attention to the parts they don't think are beneficial.