I think you may be confusing old and new with age instead of maintenance design. Boeing trumpeted the B737NG as requiring less maintenance than the B737CL that it replaced.
LAME inspection during turns was outside the MM in most cases and in Aus and NZ LAME turn checks were the norm. In NZ LAME's were removed from the domestic line early 2000's.
I am not saying it is a good or bad move, but was the customer prepaired to pay a premium to have a LAME look over an aircraft every time it landed? The rise of the LCC answers that one.