Glenn,
My 102 has a fuel settling bowl, with a screen on the top to strain larger debris from getting it into the carb. The bowl does a good job of catching water that might get into the gas tank, and keeps it out of the carburetor. An inline paper fuel filter might do a better job than the bowl to catch the smaller stuff, but the bowl will be better than nothing, which is what you get with the petcock. My 129 has just the petcock, I suspect it was purely a cost-saving move on IH's part.
I see several cost-cutting moves that are evident between the 102 and the 129. The petcock is one, the brakes on the 129 are less robust than on the 127, and I'm not sure that either were any better than the internal brake on the 102. I also liked the Ohio Rubber seat on the 102, the conventional vinyl over foam seats that came later were no more comfotable, and seemed less durable than the white rubber seats. That being said, things like the quick-attach brackets, hydrostatic transmissions, and the wider frames on later models were definite plusses, but we did lose a few nice features on the later tractors though that were present on the earlier ones.