I think that warriors are extremely difficult to play. As a warrior, you're in the center of the action. You are usually the point guy who is responsible for calling targets and making decisions on aggro, but your proximity to the combat makes it difficult to zoom out and take a bird's eye assessment of the situation. In contrast, when I am using my Ele, I can constantly scan the field, looking for new threats that have entered the fray and checking on my comrades' status. Many times have I rescued the monk from certain death only to have the warrior show up at a full sprint just as the danger has passed. They always mumble things like, "Sorry... I was busy taking down that warrior boss."

The other thing that makes life difficult for warriors is that the adrenaline system makes running from fight to fight without a pause a very attractive option for warriors. This is completely the opposite of how it works for any other class. In a good party, a bad warrior is certain to die because the elementalists and monks will refuse to charge after the dimwit until their energy is back up to acceptable levels. This doesn't happen very much in the early game, but I see it a lot from Kryta onwards.

The reason you see loads of "paladins" is that people know better than to bring them into their parties, so they all just hang out in town waiting for some unsuspecting noob group to take them in :P Everyone else is out on the missions :)

If you want the ability to take lots of punishment or if you want to run through areas by yourself without stopping to fight, warrior is the class for you. The answer to the question as to whether warrior is the easiest class to play is the same as for any other class: it depends on your style of play and your preferences.