disc brakes

[TigerMom]

I've been perusing the web, looking at what's new for 2015. It seems like there are more and more bikes with disc brakes. Do we really need them? It seems like I've been doing fine without them and now they seem like a "must have". (I'm very skeptical when it comes to marketing ) Are they easy to maintain and adjust? Do they add much weight to the bike? Please share any pros and cons. Thanks!

When the disc brakes for road bikes trickle down to the Shimano 105 range, the price of road bikes with disc brakes will not be as expensive as it is now. I look forward to the road bike disc brakes because then the carbon wheelsets won't wear down like they supposedly do now (racers use carbon wheelsets in races but practice on aluminum wheelsets because the caliper brakes supposedly clamp down on the carbon rims in carbon wheelsets and thin them down too much plus the grip is supposedly not as good when you go down steep inclines). But, the hydraulic brakes do squeek more on road bikes, at least they seem to squeek a lot on my friend's road bike's disc brakes. My mountain bike disc brakes don't squeek much at all compared to his road bike's. Weird.