They cost almost nothing, require no special infrastructure and still have absolutely zero loss over distance.
Also, with the new Buildcraft energy system introducing power perdition (passive energy loss) to the machines themselves, it can be a disadvantage to use conduits in some cases, because the conduit will evenly split all power between all destinations. If you have a big assembly table setup with 12-16 lasers, that's a massive power sink even if nothing is being lasered (between 0.5 to 1 MJ/t passive loss per laser). Conduits will always treat that passive power need as equal with all other machine's needs, so they're constantly routing energy there for no reason.
Buildcraft pipes however operate on a first come, first served principle - the closest machine to request power gets the lion's share. So if you set up a workshop where rarely used but passively power hungry machines (assembly lasers, thermionic fabricators) are sitting at the end of a long kinesis pipe (new name for conductive pipes), you can in fact use a machine that's closer to the start of the pipe and it will get first dibs on all power coming by. Instead of going to the lasers to dissipate passively, it goes straight into your machine to do work. That means less power overprovisioning necessary.
Furthermore you can use the new pipes to throttle power input to individual machines. That thermionic fabricator over there constantly drains 16 MJ/t? Just make the last pipe section a cobblestone kinesis pipe, and it'll only get 8 MJ/t. It will still heat up to 50%, which is more than enough to smelt glass and perform its job.
Overally, they are not strictly better - they just got buffed to finally being just as useful, while still being cheaper, and offering the occasional neat trick to pull off in power system setups. Obviously if your setup is somehow impaired by the "closest machine first" power distribution, then using conduits works just as well as ever.