The seconds subdial of the AT GMT shares the same layout as the Rolex Daytona and the Speedy pro, which I believe are the standard for classic chronograph design. In classical terms, you're asking for a level of precision that is normally expected to be found in the chronograph function rather than in the seconds subdial. Given this, I think there is no pressing need for a 60 second subdivision of the subdial. It's not a feature that has ever been thought of as neccessary (just use the chrono function) or even desirable (too messy and busy). Neither will you find such subdials in very contemporary designs like the JLC Amvox DBS and IWC Da Vinci chrono. Also, don't you think that it would look somewhat untidy to have so many markers on a little subdial? I would also beg to differ that marking 60 seconds would match the 30 minute totaliser because the second subdial would have twice as many markers as the minute totaliser.
Here are some pictures to refresh your memory. The chocolate Deville (my wife's) and Daytona (mine) are some of the most brilliant chronographs on the market and they both have identical seconds subdials as indeed our beloved Speedmaster has. This is as classical as it gets. I like Omega's tri compax layout better because it more symetrical than Rolex.
Have I managed to change your view on the matter?????? What do you other guys think?????