When you've snuck into the king's bedroom and you're standing over him as he sleeps. You can't just kill him. Something always happens and he wakes up and there some action sequence. This is writing 101.

When you're the most powerful wizard in the world and your best friend can make himself invisible and walk through walls, I guess you better be very reluctant to just go ahead and kill the bad guys already. And so, they keep on making trouble till you finally kill them.

The problem with the cycle of arawn is that it isn't dark enough. You know it's all going to work out just fine. The heroes have it too easy. And their banter is just annoying.