As far as I know, sram are developing hydraulic rim brakes for the road, not hydraulic disc brakes. Hydraulics have advantages over cables for both rim and disc brakes, but that doesn't mean that hydraulic disc brakes are better than rim brakes.
http://www.bikeradar.com/road/news/arti ... ook-35887/
Braking on an MTB and braking on the road are two very different scenarios - speed on the road can be a lot higher, and tyre contact patch is a lot smaller. While modulation is a good thing in any situation, the amount of braking "power" available can be too much. If you can lock the front wheel easily, then you have too much power, and not enough traction, which is not a good situation. In that case, you either need more traction so that the wheel doesn't slide, or less power to avoid locking it in the first place. If you do have a good traction/power ratio, then as soon as front wheel braking begins to lift the rear wheel off the ground, you've found the limit of it - braking harder in that case will not stop you any faster.
Good road rim brakes with decent levers, cables, pads and rims, together with a decent set of grippy tyres, are perfectly adequate for any and all situations, and while they have some drawbacks, they don't have as many as discs do right now.
Hydraulic road discs are inevitable, any manufacturer that ignores them will be going out of business.
That's why I wondered about Campagnolo, if they have the mindset that rim brakes are fine they won't have a market in a few years time.
They don't have the experience from mountain bikes like Shimano and SRAM so need to catch up quickly.