I believe this thread is more salient to the "Other Games" forum.
Speaking for myself, gameplay, storyline, and strong, identifiable characters are key. Especially true in CRPGs but also apropros to most game genres as well, including our beloved SMAC. The old Looking Glass "Thief" games and System Shock 2 are still strong favorites on my machine, despite their age, over many many newer and shinier first-person games. Arcanum is my favorite CRPG out there, another with decidedly aged graphics but superb gameplay, writing, and setting.
This is another reason why tempesteruos forum arguements are going on over at Bethesda's forums for Fallout 3, a lot of die-hard "old-guard" fans clamoring for Fallout's "soul" to be maintained versus it becoming an Oblivion clone with Mad Max overtones.