QUOTE (CrimsonWeltall @ Jul 31, 2015 -> 02:35 PM)
A pitcher's overwhelming value is through pitching, which no position player does. The DH's duties are literally a subset of the other position players. He does less, and that has to be noted.
To put it a different way: a pitcher pitches because he's awesome at pitching. A DH DHs because he sucks at defense.
Adam LaRoche may not be hitting right now, but he sure doesn't suck at defense and is a DH.