There's also the case of the people who never owned a PS3, and might want to play one or two PS3 titles on their PS4.
Personally I'm hoping to play MGS4 over this Gaikai service.
again i would expect this to be an extreme minority. everyone buying the ps4 will be buying it to play ps4 games.
i always thought BC should be included but now i think there is no reason to do so simply because i have never used it on a regular enough basis.
i think i may of played a handful of ps1 games on the ps2, but they were great classics (driver, destruction derby, gran turismo, etc). the ps3 on the other hand, i dont think i played any or 1 or 2 at max (i had a BC launch console).
also surely this Gakai service will have limitations on actual image quality, lagg, etc if it is going to be streamed to you. I am not so keen on it, would rather they just focused on the PS4 side of things tbh. If people really want to play ps3 games buy a ps3, they can be picked up for practically nothing these days.
Again people will complain they do not want 2 consoles, but again they are a minority who want BC therefore they have to like it or lump it. No point on compromising something in order to please a minority. I mean the funds, technology and staff working on Gakai could have been devoted to another use making the PS4 experience better rather than BC, or simply not needed making the console cheaper to buy in the first place.
I would have rather they went down that route personally. But I think they have went down this route to be innovative, we will need to wait til the PS5 to see if such a service is also included on that to see if they actually think it's worthwhile including such a service, imo it isn't.
Look at it this way, what if someone wants to play PS2 games? or PS1 games? they need to buy a PS2 to do so, so I don't see what the big fuss is on BC, people don't tend to play last gen games when they have bought a new gen console. Only people who dont have a new gen console tend to play last gen games.