Hardness of approximation without the PCP theorem An important application of the PCP theorem is that it yields "hardness of approximation" type results. In some relatively simpler cases one can prove such hardness without PCP. Is there, however, any case where the hardness of approximation result was first proved using the PCP theorem, i.e., the result was not known before, but later a more direct proof was found that does not depend on PCP? In other words, is there any case where PCP appeared necessary first, but later it could be eliminated?
An example is this paper:

Guruswami, V., &amp; Khanna, S. (2004). On the hardness of 4-coloring a 3-colorable graph. SIAM Journal on Discrete Mathematics, 18(1): 30-40. link

Using the PCP-Theorem, Khanna, Linial, and Safra (2000) proved that it is NP-hard to color a 
3-colorable graph using just 4 colors. Later, Guruswami &amp; Khanna (2004) gave, among other nice things, a PCP-free proof for the same result.