Aluminum can be engineered to give a beautiful ride! The real problem is it takes engineering and expertise (read money) to build a decent frame out if steel, aluminum or carbon fiber. So as long as you keep looking at the bottom end of things - you'll be disappointed.

There were bikes in the 80's and 90's that sold for over a $1,000 which was a lot of money back then. The frames may not break any technology barriers compared to some of what's on the market today, but high end older frames are IMO, better than new low end frames today - regardless of material.

I'd second the recomendation to look for an older road bike and to do a flatbar conversion. My 1988 Miyata was 21.8 lbs with 23c tires and putting flatbars and 25c tires probably wouldn't change that. Tire width is the only real limitation on a road bike - 25 or 28 is pretty much the limit unless you trip across a touring model with cantis.

In the long run you're much better off with a frame that fits and a riding position you like rather than the lightest bike anyway.