I'm pretty sure most publishers wouldn't fund a 2D, isometric, old-school CRPG, even if it only cost $1 million to develop and market. Publishers are interested in making the most profit possible. An old-school RPG wouldn't be profitable enough for them to even bother. This is why most publishers stick with big-budget, high-profile, multiplatform releases in mainstream genres (and mostly sequels at that). Sure, games like CoD 2012 and Skyrim cost a lot to develop and market but the potential profits are far greater than any low-budget, niche game could ever achieve.
Also, your GOG comparison is invalid because GOG is not a publisher and they didn't fund the development of any of the games they sell. Publishers only allow them to sell their older games because it gives them another revenue source with a negligible investment.