The point of the one stop difference in portrait shooting is quite different from the point of one stop faster for telephoto shooting, your comparisons are weak and your argument disingenuous.
Shooting telephotos: compare a 300mm f4 at 1/125 second to a 300 f2.8 at 1/250 second, that extra shutter speed could well make the difference in subject motion or camera shake and is the primary reason for fast telephoto lenses, being able to achieve higher shutter speeds.
Shooting portraits: 135mm f2 at 11 feet, for a 3" dof; 100mm f2.8 at 8 feet (for the same framing though fractionally different perspective) for a 4" dof.
Now you can argue this as much as you like, but I know that practically nobody could tell the difference between the two images shot in the portrait scenario. Sure people will pay thousands for an extra stop, I have two 300 f2.8's and have never touched a 300 f4, but in portrait shooting, unless you are plying the one trick pony of ultra narrow dof, the one stop faster turns out to have very limited functionality, the macro IS on the other hand has functionality in bucket loads.
Yet again, I am not saying the 135 is a bad lens, is isn't, it is a superb lens (though long overdue a makeover), indeed Zac Arias stated that lens alone is worth owning a Canon system for, though he ended up not using it much, favouring the 85 f1.8 ( http://zackarias.com/for-photographers/gear-gadgets/canon-switch-update-all-is-well/ ). But unless you are going to primarily shoot at f2 then there is nothing the 135 has over the 100 macro, indeed once you do go to f2.8, a mere inch difference in dof, then the 100 macro has many advantages over the 135.
If you have that mentality, go shoot the 70-200 f4L IS. No one will be able to tell the difference between the 2.8.