Piku is right - FSAA does have an effect in D2, and you can see the effect on static objects such as chests, walls or various buildings and not just on spell effects, smoke, etc. If you have a V5 use a batch file in your Diablo folder with the following in it -
set fx_glide_aa_sample=4
set fx_glide_aa_toggle_key=144
game.exe
Running this batch file to start the game allows will allow you to see the effect of FSAA by toggling it on and off with the Num Lock key. It doesn't have such a dramatic effect as in other games but it does IMHO make the game look better. Strangely it does nothing for the main character but the effects on NPCs or static objects is definitly there.