I remember getting one or two of those supposedly for my kid brother when they became available over her in the US.In the UK at least I would say it's at least 70% responsible for the 80s RPG boom.
(There is very little in the UK RPG scene that isn't connected to Steve and Ian in some way, eager little bastards that they are).
I think the CYOA books are great as a lead-in to RPGs because they can be frustrating, due to lack of any mechanics beyond Choose one of these two or three possible courses of action and see what happens.
I think of a few easily explained ways that even the most mechanically basic RPG and an inexperienced GM are a massive leap forward over that, which is really why I wish the experience of CYOAs was still common.
A week ago, I was asked by a friend who was not familiar with RPGs to explain D&D, as a mutual friend from work was talking about the campaign that they were running. If the friend in question had played/read CYOAs, it could have been done in all of about 5 minutes.