Ignoring the current debate since I don't feel like reading every comment at the moment, I'll simply stick to the original topic at hand. No, I don't necessarily believe all games are equal. Even if you were to boil it down to "did I have fun?" as the general starting line on good versus bad, we can still argue that the level of "fun" one may have is still subjective. People had fun playing FFX and XIII, it boggles my mind how you can do so, because I found both games to be boring experiences, but at the same time, I can't say my opinion is somehow an objective truth. I have fun playing older, usually nightmarish hard 8-bit titles, but some people consider them as fun as getting a root canal without anesthesia. I'm not going to argue they are wrong if the game does not have the features one derives their fun from. The best I can do is try to articulate where I'm coming from when I say X is good and Y is bad. Yet I know I'm talking the extremes and the original OP was talking more about a "good" game versus a "great" game and how branding affects our views on this matter.
Recently I've been going through FFXV and before that, I had finished up I am Setsuna. In my current mood, I would argue that I am Setsuna was the better game for me, but I would also state that had I am Setsuna been FFXV and FFXV was Brotrip: The Last of the Kings, that opinion may very well change. This is because brands do paint our perception of quality. Brands exist because they have a history of a certain quality and as that history grows, so does the expectations, even if that expectations is simply unreasonable due to looking at past glories through rose-tinted glasses, and frankly that 's just the unfortunate predicament that many long lasting game franchises have found themselves in.
I didn't go into I am Setsuna with any high expectations, while I was certainly excited for it, I didn't go in thinking it was going to be as good as the nostalgic games it apes, and frankly that expectation was met, but I still found a lot of things to enjoy about it because it hit most of the criteria I need to find a game engaging. Despite my best efforts, I went into FFXV with some form of expectation and it certainly surprised me more than Setsuna did. Yet for all of its merits, the game has certainly got a number of flaws as well. Course I could easily argue that even the "glory days" weren't short of their own faults, but nostalgia is a cruel mistress sometimes, and it sucks that good games have to be judged long after the fans have moved past their impressionable years. If I was fifteen, it would just be as likely for me to consider FFXV to be one of the greatest games ever made, but I'm hardly that age, I've been around the block too many times, I'm not as easily caught in wonderment like I was when the world was expanding around me in my formative years, and I'm old enough now to know what I like and dislike, and even brands can't necessarily change that opinion.
XV already had to deal with my opinions on things: how I feel about open world games, how I feel about ARPG combat, what I expect from characters and story. It was no different with I am Setsuna, but the difference here is that I went into Setsuna pretty certain it would under perform for me, and I was pleasantly surprised to see that assessment didn't always hold true. It's easier to be surprised when you are dealing with people you don't know. I've never played anything done by TRF's staff so I went in blind with just an opinion formulated from what I knew about the game. Final Fantasy and I have had a long history together, Tabata has been around long enough for me to have an idea of how works as a director, so of course I have certain things I look out for, and thus XV has a greater list of criteria to fulfill for me. It's just the nature of brands to build an expectation of a certain quality, and that quality doesn't necessarily extend to everything within the medium.
Does it suck when a good game is ostracized due to insurmountable expectations? Yes, and I've seen my fair share of great games denied their rightful glory due to fans and the unreasonable quality we hold them to. Hell, I myself have done it, and I'm sure I've missed out on some great games cause I couldn't look past my biases and stubbornness.