What's the scope you are aiming for with this mod? Currently it's just pipes, right? Like you said, pipes aren't fun on their own, but since these bring something new to the table they could be very fun when combined with other mods. Or, do you want to turn this into a mod that's fun when it's standing alone in vanilla? If so, you're going to need additional content in the same sense that quarries add to Buildcraft, pipes alone won't cut it.