Not to be a patronizing old fart, but may I assume that you played II after III? If so I can understand it, but II was very special when it came out, and I never revisited it after.

I think it's a case of being better when it came out than another thing was when it came out, despite the other thing being comparatively better without the context of its time.

2 is a much harder game in my opinion. I don’t think even at the hardest difficulty level Warcraft 3 has any levels that require you to do a contested marine landing and then build a base before immediately being attacked again. The final Orc mission took me forever to beat. And the expansion? Good lord.