The knife cuts both ways here, and WoTC have little room for maneuver. Cards from the basic set might not be compatible with Portal Rules (none-creature permanents, Instants) and so there are onyl so many basic set cards that can be included in Portal. The other cut is from portal, that so many cards ARE sorcery equivalents of existing Instants that using them in basic edition or expansions would make them very boring indeed. There are very few cards that can translate from Portal to Standard satisfactorily, and to WotC`s credit most of those ARE used. While Portal remains seperate in rules it will necessarily remain largely seperate in cards.