The situation can only do so through interaction with the rules.
In any case, the warlock is like the ninja of spellcasters. He teleports. He gains temp hp to become more durable. He cloaks himself in shadows as he moves, and with skill even vanishes fully from sight. The game designers wanted to encourage dynamic combat, so they gave his magic a special rule- his curse only works on his closest foe. This makes you want to move so that your closest foe is the best target for your attacks. Then, because they wanted to make you enjoy moving around, they gave the warlock a ton of mobility related powers and tricks.
If this were removed, the warlock would turn into an artillery class that sits in the background and fires away. Now, instead, its a tactical skirmisher that strikes from the shadows and fades away. For most of us, this is much more fun to play than would be a character who plants his feet and stays in one place.