If you want a "worth it" option, make a mixed class, then If you do get bored of multiboxing or want to stop and just play one then you have the option of 5 classes not just one out a single class.

I was always thinking too, what about the long run, what about the long term, I made a mixed group, mixed with some characters I had and some I didn't and also made a full Druid group. The druid grp I level up slowly, do a bit here and there, the mixed grp is my main grp that I level everytime Im not on my main raiding.

You just need to see if you want to do it. I know starting up can be daunting and hard work but it does get easier once the kill quests start coming in. I must admit I have quit and restarted and taken a break and re-thought about it over and over but I always come back to it as it is a new challenge to me and I love the challenge.