They're marketing it the same way Nintendo marketed New Super Mario Bros, which was also different from its predecessors in physics and setup.
Apples and oranges, again. As Blues said earlier, there still is a problem with trying to roll S4 in the same way. NSMB was a game that was marketed as a "new take" on that original SMB formula. It was
not trying to be "SMB4/5" (take your pick on numbering) any more than Yoshi's Island or SM64 was. It was meant to be its own product unto itself. Sonic 4, on the other hand, directly tries to invoke the spirit of the 16-bit game's legacy by ATTACHING ITSELF to it, and yet then goes on a completely different tangent from what those who expect an "heir" to that legacy to do. And that's where the problem is. There's certain expectations that people have in mind when it comes to sequels. This is only more so the case, depending on which "school of thought" applies when we're talking about sequels.
For example: Street Fighter 4 was allowed to be its own beast, separate from its predecessors, because in the end, the realistic expectation was that it was not going to play like either 3S or Zero/Alpha 3. "SF4" was, in essence, the beginning of a "new series" with the SF anthology. In that same way (much as I haven't liked it at first), MvC3 has changed things up from its immediate predecessor, which even so, goes right along with how MvC2 was different from MvC1.
In this same train of thought, KOF: Maximum Impact and its sequels may have the name tag and share a number of characters, but that's where the similarities with the 2D, "mainline" KOF games end. Like it or lump it, the MI games have a distinctly different "feel" about them from the 2D games, so you can't crucify the spin-offs for being what they're clearly NOT trying to be, or otherwise emulate. That's like hating the Sonic Rush games for not being verbatim to the Genesis games. The Rush games were clearly trying to do something else, and thus you'll either love or hate depending on the games' individual merits. (Oh, and please believe I got plenty in that area alone!
)
On the other hand, games like Tekken 6/BR, for the sake of our fighting game theme, have a different set of expectations. People expect successive games to play like an improved version of what they got before. In fact, Tekken 4 is widely-considered the worst game in the series because it did a lot of things to its own, as well as the series' detriment (especially coming on the heels of the widely loved 3 and Tag). That's why the later Tekken 5 had to do more to clean up 4's mess and get back on track. And we can more than likely bet that the "Next Tekken" game (already in the works, and stands to be out before Namco's Tekken x SF game) will likely do more to follow suit.
In this same vein, that's where Sonic 4 falls for guys like myself. It's not what we expected from such a modern day game that tries to tack itself on to a SPECIFIC iteration of the series that carries a certain amount of weight with it. If Sonic 4 was named any thing else you or some other PR schmuck could imagine, that would have perfectly fine. The game would then be able to be judged as an entity unto itself, not unlike the Rushes, the Storybooks and everything else that came before it. Who knows, maybe the game, as a proposed "Sonic Retro" that's not connected to anything else, could have been something special. But now and forevermore, 4, and any games attached to it, will always be judged by its immediate predecessors within its lineage. And again, that's the crux of the issue. It has NOTHING to do with Sonic 4 as an individual game any longer, and everything to do with if it can live up to the high bar that Sonic 1, 2, 3&K set for it. And you only have the brilliant minds at Sega to blame for pitting the game up against such a tough act that, at this rate, it can't hope to follow.
Very well structured on that scenario PB, but people like Ben could be extremely butthurt and continue to keep bringing up the negative parts of the returant even though he/she has stopped going there ever since. It's kinda like beating a dead horse. Plus I think it's the consumer's/owner's actions, not the chef's (This case, the programmer's) fault (Due to them following what the lead developer wants to see, rather than touching things up).
Say Sega's still correcting it's errors. due to the extremely poor reviews given by hypocritical critics, it makes it hard for them to earn back thier consumers (because they follow the critics around like mosquitoes, therefore they take the critic's word for it and spread it around like wildfire), therefore losing half thier salary.
And you know what?
It's tough, but fair. Sega, like any body else in this industry, is in it for number one, and they're certainly in it for the money. That's what capitalism is all about. Everything is fine and dandy as long as the consumers and the shareholders are happy. It's when they aren't, THAT is when problems start occurring. If such "establishments" don't see the issue when such a thing happens, well, that's an even bigger problem.
So, when Sega does bone-headed decisions like those concerning Sonic 4's development, the shoddy PS3 port of Bayonetta and cutting out content from Yakuza 3 (which there are still TROPHIES for!), they can't exactly be expect to be rewarded with such behavior. If they don't like the "bad press" that ensues, then by all means! DO BETTER. Take a cue from Domino's Pizza, for crying out loud!