An interview on Gamasutra chats with Chris Avellone of Obsidian Entertainment about their upcoming Project Eternity, as well as some of the old school RPGs that inspired this upcoming release and the successful Kickstarter that got the project underway. He offers the following outlook on what RPGs like this fell out of favor with publishers:

I don't know if I have a good answer for that. I do know that there's one technical limitation: when you're developing an RPG for the consoles -- which most publishers want because it generates the most revenue -- it's often very difficult to control a party of characters, with either the PlayStation controller or the Xbox controller. So that immediately causes you to change the dynamic of how you design the RPG. You can have two party members with you [the player], but you've got to recognize that that consumes a lot of memory right then and there. And you also have to set their AI states -- you're not really controlling them.

A lot of those [Infinity Engine] titles were PC-only, and that's not really an appealing pitch to any publisher. They don't really want a PC-only title, because that's not going to maximize their revenue.