The problem with reprinting magazines is generally down to who owns the rights to all of the content. With a supplement or adventure you're dealing with only a few people, but tracking down the rights holders for a magazine is a huge task.
Dragon, White Dwarf, Heroes... they've all had PDF releases that were hastily withdrawn. Although some magazines are available electronically (you can legally obtain copies of Space Gamer andFantasy Gamer, for example) they tend to be the exceptions. Gaming mags rarely made money in print, so it's hard for a publisher to justify the expense and effort involved in republishing them thirty-odd years later.
Those where because of rights assignment in stead of sale of rights. GDW and whomever was doing SG/FG before Better Games bought the rights to most articles, where TSR (and later, Paizo) merely licensed. Early WD vs Late WD gets even nastier into complexities, due to the buyouts of GW. So, all of the articles for JTAS (GDW's Traveller house organ) were purchased; Challenge included reprint rights (including collections in bound volumes) in their standard. So only a few things are blanked in the Challenge CD.
Supposedly, SJG owns all the rights to old SG/FG except the Better Games era. And BG's Red and Conrad generated most of the content, and still (kinda) are doing business as Better Games. They've made their non-magazine format versions into PDFs.
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