Yes it just comes down to if being a vampire can be a good thing or not. Because you are right, empathizing rarely actually helps the other person. Sometimes it does, but the real reason for acting that way is selfishness.
Vaknin is right, that we do things like that so we don't feel guilty. My senses are like obligated to try to help someone if I can, but it's not really because I'm a good person. Sometimes I'll go out of my way to help, but for the most part. Empathy is about not feeling bad about myself.