Why don't they make songs like ramblin man anymore?

A song like that just makes you wish music like that was still played on mainstream radio.

The mainstream radio for "country music" wants you to hear the "glamour" shot singers,The Mainstreamclassic country is shelved as in apropriate for the "MASS listening audiance".
Keep my country pure,keep it classic.

People still write songs like that (it's just radio won't play 'em)

mostly because there will never be another Allman Brothers band, especially as they were at the peak of their powers. Truthfully, that was the apex of the 70s Southern Rock scene.
there will be some good songs yet on mainstream radio, I am sure. But you are correct in that they seem rare...

More than likely because of that Hip-Hop mess that they play to please the low-lifes!

those type of songs are still out there, radio just plays the pop country crap..