Starting off small, there would be a clear difference here.
One is an iconic series that is a big Japan pick that also has seen recent success on a huge scale in the West.
The other is Overwatch.
Tracer =/= Hero even in the sense, as you cannot compare the series to each other in the slightest. Dragon Quest isn't just a shill pick, whereas an Overwatch character couldn't be anything else BUT a shill pick...and by that I mean Blizzard someone offered Nintendo so much money that Nintendo dropped their morals.
Overwatch is not relevant. If Blizzard would let it die, it would. This may be anecdotal, but it's also still proof.
Back when Overwatch was still big, literally everyone I knew had a copy and was playing. Even my old roommate played it, and he was known for only playing JRPGs and Smash. It wasn't too long though before it died out, mainly due to Blizzard's lack of listening to the fanbase but also due to the dev team having members with god complexes and trying harder to appeal to those outside your demographic than to those within it. We've seen enough of this recently to know what happens.
Regardless, it's nowhere near where it was before and it keeps fading.
There is a difference between us getting hate for truly loving our character and supporting him and not wanting Tracer because of what she represents. In case you are wondering...
She represents many things outside of just herself. She represents her game and the genre, which is a dead genre and a game on life-support, so as I said earlier her inclusion would be nothing short of everyone knowing that Nintendo made big bank off of Blizzard. She represents Esports on a level that Smash has never obtained, both in popularity (albeit brief) and toxicity. The fans that would come with her would make this awkward dent in the Smash community as they bring in their baggage and their attitude and I'm not sure if you've noticed or not, but the community has enough of it's own drama without including more. As bad as Smash fans can get, it's usually all outside of the game, not in game. Now imagine all the Overwatch players who come over and bring their in-game attitude to Smash. I never thought I would be glad that Nintendo's voice chat option was so out-of-touch...
This one will ignite some fires I'm sure, but she would also represent her orientation. To be clear, I'm not declaring anything about her orientation on it's own merits (other than how tacked on it felt), but you can be sure her being the first character in Smash to openly be of said orientation would be a big deal in more ways than one and would garner a whole new ball to add to this juggle session (remember,
got a feather removed because people got overly upset over something so minute. Imagine if people felt Tracer wasn't 'good enough' or that she wasn't 'represented properly' or how upset they could get if she ended up being middle tier?).
She also represents controversy about her from within her own game, forget what could spawn from Smash. She also represents a company that Smash fans seemingly very much dislike, which makes a lot of sense when you compare Nintendo to Blizzard ("You all have phones, don't you?!" and "You don't want that. You think that you want that, but you really don't want that." come to mind immediately).
There is probably more I missed, but if you could somehow erase ALL of that baggage and someone magically make her a part of a game that was better in every way and from a company that was much better...I think she could easily work in Smash. I think she has enough potential in her moveset to whip up something, and having a character with time-wimey abilities in Smash that were less passive than
would be pretty cool...but I must say Tracer really isn't all that wanted by the community. Once again, not that she isn't wanted at all (as you yourself are proof enough and I know there would be others) but she's not on the same scale as others, and if she got in before any of the other big names I would be livid.
To sum it up best, there is a difference between having a fanbase's toxicity revolve around them, and having a fanbase's toxicity encompass their game. One can seem ungrateful and irritating and irrational and rude...and the other has all this AND acts like this in-game. It's a part of Overwatch's basic community now and you can encounter it in way too many of the matches you play.
Smash is lucky enough to have something most games don't have: a clear line in the sand between casuals and competitive players, on which side each can enjoy the game. Overwatch is for aggressive competitive players only and the experience shows.
Also, this isn't really hypocritical for Geno fans to not want Tracer or anything Overwatch in Smash. It's on the same level as not wanting anything Fortnite or Apex Legends in Smash: there are bigger fan picks that have been asked for for LITERAL years, over a DECADE now, and having characters from games that will be dead and forgotten in due time that are made just to rake in cash and made by greedy companies with egotistical and morally-questionable devs is a slap in the face. I tried coming up with analogies that would be less direct but I just can't think of one that works well enough, so I'll just have to leave that sting in there.
All this said, feel free to enjoy the game and feel free to want Tracer to make it into Smash. Just because others don't like something doesn't mean you have to stop, and you can like Tracer and still want Geno. I would never hate on you for a character you want or a game you love because that just doesn't make sense. All I ask is that if I can respect the fact that you like Overwatch and would love to play as Tracer in Smash, that you can respect the fact that Tracer being part of the Fighter Pass is one of the few things on my list that would make me not buy Ultimate and wait for the next entry without her in it from the sheer anger at Nintendo for dropping not just the ball but the whole goddamn court in my opinion.