i view yuri bait as fundamentally different from het ship teasing, because of historical/societal treatment
Yeah there's a difference in treatment and historical/societal treatment as you're saying, though sometimes relationship teasing is the best that the creatives can do due to the people in power and companies in charge of things. A lot of times creatives are forced to work with companies that provide money but have a lot of say over the project, it's often a difficult relationship that restrains the hands of creatives. I often find there's a lot of nuance and so forth to these situations, which I think that's a big part of why I don't want to classify creatives as insincere without having all the facts. That's also part of why I don't want to use "Bait" as freely as you do, I see that term used so commonly for so many pieces media and relationships that to me it feels like it's commonly doing more harm than good at this point.
these days
I'm generally not a fan of this sentiment myself, because in my opinion there's a lot of sincere media out there that's being made. Also that in my experience people look back at older media very fondly through the lens of nostalgia, while ignoring any problems, and saying basically no or very little modern media has any value. I see people say all the time that there's been no good music, anime, movies, books, tv, games, so on made in the last 20-30 years, and statements like that genuinely make me sad and frustrated, because I've seen passionate creators making fantastic media every year, including media that I'm personally not into but other people love. I believe there's always been a mix of things no matter the time, and it depends on where you look.
With same sex relationships in modern media, there's two somewhat recent live action show adaptions of manga that are focused on lesbian couples that come to mind, and I don't think we would have gotten those back in the day. Or the various upcoming anime adaptions of Yuri series such as Green Yuri. Even the marriage elemental in GWitch feels like a massive step forward even with the series not showing a lot, they are in fact a married same sex couple. I don't think GWitch or the people that directly worked on the show are insincere about the relationship, more so that there's a lot of red tape people still unfortunately have to work with, including that dumb Bandai producer that was an ass about the relationship, and yet creatives are still making important progress. With the West you have people doing their best as well, Disney screwed over Dana Terrace and her team with Owl House, and yet she still made an incredibly sincere and fantastic series with a wonderful same sex couple. People are trying, we're getting more progress bit by bit in some ways, and unfortunately companies and people in power want to push things back, the best we can do is keep pushing forward.