First off, I think the "oh noes its by Sonic Team" thing is bullshit. Sonic Team gave us Unleashed, Generations (which in what way is a "fluke"?), Sonic Colors, and Lost World (which is a good game). The bad Sonic stuff from 2008 onwards mainly came from bad business deals from upper management (Nintendo exclusives, Boom) and external developers like Dimps and BigRedButton. At the anniversary party when they showed the Sonic Team trailer and name dropped Generations and Colors, I thought it was worthy of a well earned cheer. Whatever negative stigma people claim the Sonic Team name carries is their own personal bias by this point.
Basically Sonic Generations was a hope spot wedged between many games that have received mixed to negative reception. In a sense, it was the exception to the rule and as a result for SEGA and Sonic fans they finally had something universally liked, and it gave hope that the series can finally get out of a rut that's arguably been plaguing the series since the mid 90's or 2005-ish. Which sadly got contracted by the later Sonic Lost World and
especially Sonic Boom. So while Sonic Generations gave fans the hope they needed, it just ended up being a fluke in the long run.
Also ironic that you mention Nintendo exclusives and Dimps harming the Sonic brand. In fact, several of the better received Sonic games were exclusive to Nintendo consoles and developed by Dimps like Sonic Rush. Yes, this also includes Sonic Colors. The thing with Sonic Lost World and Sonic Boom though is that they were doomed right from the start. Sonic Lost World went far too deep into experimenting territory right after Sonic Generations proved they had a working formula, and the game as a whole ends up being confused as to what it wants to be. Sonic Boom meanwhile was always destined to be a mediocre game. Even if you put the game on technically stronger platforms to fix the CryEngine problem, it still wouldn't fix the fact that the game has problems like very monotonous combat and a very bare plot that fails to be a prequel to a new continuity. Some would argue it could of been fixed, but since the general Sonic Boom franchise has been conceptualized since at least 2007 or 2010 (that's another kettle of fish to talk about) and the Wii U/3DS thing was basically last minute, I doubt it.
As for Unleashed, it in a similar vein to Sonic Lost World was a victim to experimenting. After Sonic 06' horribly tainted the reputation of the brand, they needed a drastically different direction so to help fix the brand. Though unlike Sonic Lost World, it had something working for in the form of the Daytime stages, and it's often cited as one of the game's strongest aspects. Sadly the Daytime stages despite being well received, were overshadowed by the more prominent (especially in the Wii/PS2 version) Night stages. I know it's a cliche to complain about the Werehog, but the general mode feels like it's trying to be something like Devil May Cry or God of War, but it misses it's mark. For example, stages having a habit of being too long and tedious, redundant moves, and hit detection being shoddy in certain spots. The concept could of been an enjoyable novelty if given the right execution, since those type of games are proven to have worked. That's a problem, but even the Daytime stages have some rough areas that get fixed in later games like Generations. So Sonic Unleashed is in general a step in the right direction, but because of a big misstep the game felt like it missed potential to be something better. I mean it
was one of the games that was pulled from circulation for a reason.
As for the Sonic Team thing? Keep in mind with that particular development group, it's pretty much in-name-only. Many of the key people that made the Sonic games on the Genesis and the cult classics on the Saturn like NiGHTS left. Naturally when people that help make the entire system work in the first place leave, you're left with people trying desperately to fill in the void, and because of the constant restructurings it's one of the reasons why many of their games have a habit of being inconsistent. Sonic Team by technically is involved with other games, Puyo Puyo being an example, but because the "Sonic Team" logo is heavily associated with Sonic to the point only Sonic games actually use the logo these days, naturally people associate Sonic Team with Sonic. This as a side effect means that Sonic Team gets the blame for anything that goes wrong with a Sonic game. Which is especially jarring because the other games the division is involved with tend to be competent, yet kept quiet about it. To be honest, I can see why people would be uneasy whenever the Sonic Team logo shows up, since they're inadvertently associating themselves with flawed games.