Forgive my ignorance, but what is the practical difference between "interpretive theory" and an opinion piece dressed up in an important-looking suit?
What domain of inquiry are you talking about?
In academic disciplines, the difference is depth of inquiry. There is just no comparison, for example, between the depth of Weber's comparative historical and sociological research, and that of the typical NYT columnist.
When it comes to RPGs, there is no academic discipline, but depth of inquiry still makes a difference. One striking feature of discussions and essays at The Forge is the range of games discussed and played, and the detailed attention that is paid to the published texts for those games.
This contrasts with, for example, claims one sometimes sees made about the depth of simulationist or immersive play supported by 3E, for example, without any apparent familiarity with, or comparison to, other systems (such as BRP/RQ) that also aim at this sort of play. Or claims made about how skill challenges just
cannot provide anything but a die-rolling experience, without any apparent familiarity with, or comparison to, other systems (such as Maelstrom Storytelling or HeroWars/Quest) that use similar action resolution mechanics. Or (and this one I remember from the ICE boards) claims that a game in which equipment is bought using points just
cannot make sense or be played in a verisimilitudinous world, without any apparent familiarity with, or comparison to, points-buy systems (especially superhero systems) in which points buy for equipment is a standard part of character building.
I also want to stress that this has nothing to do with my own personal RPGing preferences. Look at the
class balance thread on the New Horizons subforum. Poster after poster tries to tell the OP that s/he is mistaken, or asking for the impossible, in wanting balance to be handled via GM adjudication and the exercise of force, rather than via mechanical means,
without providing any discussion of the long tradition of RPG play - and especially a certain type of AD&D play - that proceeds in precisley such a fashion. I personally don't like that sort of play, but it exists, and I would say at one time was perhaps the mainstream approach to playing D&D (at least judging from Dragon magazines of the era, the way modules are written, etc).
In short: familiarity with a breadth of differing examples, which then breaks down a person's general inclination to generalise from his/her own experience, is central to constructing plausible and worthwhile interpretive theories.