Thanks to all who responded, especially Martin & Mark who explained the reasoning behind the difference in Zone 4.
I hope I didn't sound like I was complaining about the provision. I was simply asking why the difference was there from the previous code. I also pointed out that if your structure is governed by eq. (30-7) for base shear design (not just for drift design) and then you ignore the 1.3 Ta cap, you are designing for a worse case than that for desiging frame elements when checking drift because the higher the period, the more the vertical distribution is thrown up toward the top level (i.e. - Ft gets bigger or closer to the 0.25V limit).
It seems that everyone is confused. Mark G. also stated that the vote was not to use this equation but It never got into the code. I can't see why it has taken more than 3 years to resolve when I believe there has already been two erratta published from ICBO. I suspect that something else is going on here.
I had heard about the errata from others in my office, I knew it was coming, and the name of Mr. Hooper came up as well. Is there some sort of Conflict of Interest he may have here? I don't know who he is, but the last post from Ben Y. stated that it came from his firm. Is he a code committe member or something that makes Ben Y. imply some level of impropriety? Just thinking outloud here ....
Again, thanks to everyone and any updates you hear, I'd be appreciate it if someone could post it for all to see.