I'm far from a PnP expert, but I think BioWare's rationale can be traced to the Player's Handbook:
Elves
Elves tend to be somewhat shorter and slimmer than normal humans. Their features are finely chiseled and delicate, and they speak in melodic tones. Although they appear fragile and weak, as a race they are quick and strong.
The players handbook is superceded by campaign setting specific material; that's the point of having specific campaign worlds like FR or Dark Sun, Dragonlance, etc. The rules/ceddescriptions introduced by campagin material replaces/updates/supercedes the core books. FR elves have always been as tall as humans, al beit more lithe in build. I simply don't understand why bioware chose to go this route; surely someone pointed this out to them over the years since they put out the bg games then nwn1, nwn2, etc?