I too have an aluminum fork on my steel Specialized Allez from the early '90s. I've thought of switching it out for a carbon fork too, though I imagine the weight savings won't be dramatic over the aluminum fork, but it should give a better ride. My aluminum fork is pretty stiff, though not uncomfortable. It seems to be designed well.

Other than weight, is there any other reason bike makers briefly went to aluminum forks?

If you like the way your old quill stem looks (I like mine), Cinelli make a pretty cool-looking titanium stem for threadless carbon steerers called the Grammo:



and it's pretty lightweight.