Originally Posted by Longfemur

It's because consumers have long expected lighter alloy (and now carbon) components even on more utilitarian bikes. When typical transportation-type 10 speeds were made with all steels components, and all the lubricated parts could be lubed with an oil can in just a few minutes, a bike could literally go for almost decades with very minimal attention if any. They were heavy, but the upshot was that they required very little maintenance. They were also pretty simple to work on if you did develop a problem. But we all want light, and the price we pay is more frequent adjustment and overhaul.