The idea is to give casual gamers the experience. I have a 'real' Intellivision with about 35 or 40 carts. I keep it stored away, and have the Flashback connected to my TV. For most INTV game it's close enough.
I think since the Sega Genesis Flashback has an actual working cart slot that they should probably do that for all of them. This would especially be appreciated on that flippin' Diva of a console....the Colecovision.