I'm suprised people had troble with AVP Classic's difficulty, an issue I had with the game was that the player felt too overpowered. As a marine you are way too fast, you can dodge aliens attacks and your guns are quite strong, as a Predator you can fight off multiple aliens fine with only your wristblades since it got good range and damage, as an Alien you are so fast all enemies look like they are in slow motion, they die before noticing your presence.
In AVP2 you don't have such advantages. If the aliens get close to you as a marine you are screwed as you can't outrun them, if you try to go melee on 3+ aliens as a Predator you are screwed, as an alien rushing at an enemy that is too far won't go well. Primal Hunt was even harder. If I was to give AVP2's hardcore a 10 on difficulty, AVP's DC would like a 7 or 8.