I don't know what you mean by 'all things being equal' in this case. But I think the penetration is very different, then to now. I also think the advance in TTRPGs since then hasn't even come close to how CRPGs have increased in sophistication over the same period of time.
I mean... like how a million dollars back then is worth more comparatively speaking than a million dollars is worth now. You say the sophistication of CRPG's has come a long way and that's true, but back when Pool of Radiance was new, I didn't look at it and go, "OMG, this is so unsophisticated!"
To me, at that time, it was the height of sophistication, just like whatever new CRPG comes out now gives the same impression as Pool of Radiance did back then.
The market today for consoles and PC games is much, much larger than it was back then. So it's unfair to compare the two without equalising things out a bit. So by saying, 'all things being equal', I mean that penetration of consoles and PC gaming is roughly the same percentage of the market as it was back then. Adjusting for the size of the market today so that you can compare to the market size of yesteryear.
In other words, all my friends and I all had C64's and NES's and before that, Atari's playing Frogger. We all had hand-held Donkey Kong's and Mario Bros. and traded them between us. Just like today most kids have an iPhone or a DS.
And we still played TTRPG's.
I still play CRPG's. I'm half-way through levelling a newer, better looking, Shepard to be ready for when I can afford Mass Effect 2. I'm dying to play Dragon Age but I'm saving money for a Macbook Pro.
But I still play in one weekly game, DM another weekly game, play LFR online whenever I can get a spot, and I'm about to join my uni's Roleplaying Society sometime this week or next. This amongst full-time study and part-time work.
I also hang out with regular non-gaming friends on weekends.
I don't think I'm alone in this level of activity. I think it's about normal for most people. Point being, just because I play CRPG's, doesn't mean I don't play TTRPG's or have a social life outside of gaming.
Are kids so different today that they only play CRPG's in preference to everything else?