The cheapest 8GB module I could find[1] is £75 ex VAT, 4x is £300 which is approx. $490USD. I think this compares fairly well with the $400 upgrade pricing on that rumour page.
[1]http://www.crucial.com/uk/store/partspecs.aspx?IMODULE=CT8G3...
http://www.newegg.com/Product/Product.aspx?Item=N82E16820239...
http://www.newegg.com/Product/Product.aspx?Item=N82E16820148...
In their new laptops, it's soldered to the system board so you can't swap it, anyway. (So max it out up front)
In academia — or at least in STEM and the social sciences — quite a lot of people need a somewhat high-spec machine (e.g. to run quantitative models on large data sets, compile code, process large LaTeX documents, etc).
And the basic model Macs generally come with woefully little RAM and rather small SSDs. So I'm not sure it's reasonable to be hacked off.