You're too late, I've seen U-locks advertised with something very similar to what you are describing. A soft outer coating to defeat cutting wheels and kevlar/steel cable to defeat hacksaws.

I personally use a chain and a medium U-lock. I use the chain to attach the bike to the rack/post and the U-lock to attach the rear wheel to the bike. I personally find it next to IMPOSSIBLE to use the U-lock to lock the bike to ANYTHING other than a thin sign post or rack. The majority of the time, I'm not locking to those types of things, so U-locks are useless. It's not that it's not long enough, but with my frame geometry I always have to have the U-lock at an angle, which makes it impossible to fit over thicker things.

Also, 2 locks are better than one. If a thief wants to steal a bike on the rack where you're locked up, he'll skip yours if there is easier prey. (Assuming you have 2 locks.)

There is a video somewhere (pretty sure I found it on here a long time ago.) about a guy who tells people how to lock up in NYC (or some other big city.) He goes through and cuts through small cables in half a second and shows good ways/bad ways to lock up. IIRC he had long hair.

I never understood the whole "cable attached to a U-lock" thing. If the thief wants to steal your bike, he still only has to cut through one lock. And cables are cut in half a second with a pair of cable cutters. They offer nothing but a slight inconvenience to someone who wants to steal your wheel/bike.