People get hung up on materials. The reality is that different materials simply permit different trade-offs in the frame's design (key trade-offs are weight, handling, comfort). What has changed is that in 20-30years, technology and design/testing expertise has moved on. So, what you get with newer materials (steel as well as alu & carbon) is that you can produce frames that are both better (as well as worse) in absolute terms (i.e. better/worse along all three weight/handling/comfort components), as well as greater variation in the trade-offs between them (e.g. better tuned comfort at the expense of e.g. handling).
E.g. it's clear to me (having ridden a number of carbon frames - my current stable is 1 steel tourer, 1 steel 90's racer, 2 new alu racers, 1 new-ish carbon racer) that the ability to design specific properties into a carbon frame is unmatched by either steel or alu. The downside is cost. A good new alu frame is a generally a far better proposition than a good 531 racer (i.e. it's better in every respect, including comfort) but there are equally bad new frames out there. New steel I'm sure is great, but I haven't ridden one!
Judge a frame by how it performs, not what it's made from. Bear in mind that newer does generally mean better, because engineers are good at making things better! That said, I love riding my '96 Concorde for a whole host of reasons, mostly because it's a super riding bike (judged objectively) but also because I like to surprise people by hanging in there on fast group rides riding what many people consider a museum piece, and an extremely beautiful one at that
I get that, but my issue is that I need a new frame because the aluminium one has a crack down the front of the seat tube (just below the binder, so not an immediate issue). And whilst you are right about not getting hung up on material, it is an interesting subject to discuss prior to making the decision to order something. Im sure that any material can be made to deliver the feel that I want, need and expect, be that steel, aluminium, titanium, bamboo or indeed dried triple butted macaroni. Of course with the exception of carbon fibre; it is the work of Satan. (This is not based on testimony or personal experience; it just pleases me to berate something that these days is applied to anything and everything that need to be portrayed as high tech, so I feel disinclined to follow that particular route.)
My instinct is to get a steel frame (once I can decide on a builder) but my Aluminium success has left me in this quandary.
It would be very nice to try some modern steel frames to see if they tick my boxes, but in reality this is difficult unless there are any 6'2" riders in my area that are willing to met up to swap bikes for a little comparison...