The side that explains why backwards compatibility has been effectively killed off. You seem to think it's as simple as "Sony are evil, they want more money!" when evidently it's something they tried with the PS3 at great expense to both themselves and the customer, and ultimately it caused huge problems for them right from the start. "2 generations of BC" is something of an exaggeration too, considering the vast majority of PS3s in the word don't play PS2 games.
Ultimately, they're a business, and businesses are out to make a profit. The fact that you can't make a case for backwards compatibility from a profit perspective explains why the feature isn't there. I've no idea what it would realistically cost to include PS3-compatible hardware and software in the PS4 (including all the costs leading to it), but I can say with certainty that it's an amount most people would be unwilling to pay.
Because three people out of 75 replies have said they wanted it? All it tells me is that there's so little demand for it that Sony would have been mad to build a limited-production, significantly more expensive model just to satisfy the few who want to play PS3 games but can't or won't use their PS3.