Well what exactly are the negative externalities on the streetscape if its not the noise?
The York Street offramp isn't unpleasant, it's the massive mega highway literally right next to it, as such you can't look at it in isolation. By contrast, I think the park under the Richmond and Adelaid viaducts is actually quite nice (well was, I haven't been there in a few years now so I don't know if it has changed).
First, the location you linked is actually kinda nice, and I would absolutely love to have that in Toronto. Second, are you seriously arguing by using 19th century functional infrastructure? We don't live in the 1800s anymore, we live in the 21st Century where we are actually quite good at building nice looking els. Just look at this:
https://www.google.com/maps/@49.188...!2e0!5s20210301T000000!7i16384!8i8192!5m1!1e2, or this:
https://www.google.com/maps/@49.254...rOTw0XBPUsLbA9uRIQ!2e0!7i16384!8i8192!5m1!1e2, or heck you can even look at cities like Tokyo:
https://www.google.com/maps/@35.663...m3LEVSuCEwSedj0wTw!2e0!7i16384!8i8192!5m1!1e2
South East Asian Cities especially love putting els everywhere, and they do so respecting the urban fabric and making nice walkable areas, all without needing to sacrifice the speed and efficiency of the transit itself.
You have a source? Maybe some actual statistics to back up your claim? At best, the only thing you have here is a subjective claim on els being ugly, but even then that's extremely subjective. I can't think of any modern elevated metro that has had a negative impact on pedestrian movement and business viability, and cities like Vancouver and Hong Kong have basically proven that all of these claims are unfounded. And no, you can't just point to Chicago and New York that are >100 years old and are barely holding together due to poor maintenance.
Whatever time you lose by having to go up a small flight of stairs is made up by having a faster and more frequent train, and that's assuming that you lose time in the first place since you don't have to worry about waiting for a green light to cross the street to reach the median (as a reminder, if you have a far side stop, the train approaching the station has a green light, ie the crosswalk to the station has a red light and unless you want play frogger, you will miss the next train). I don't want to count how many times I have reached a Viva Station only to have missed the bus because I had a red light and couldn't cross Yonge Street to reach the platform, and since LRTs have much stricter limitations in terms of frequencies, missing a train on a median LRT is far more impactful and problematic than missing a train on an el. This is before we even talk get to the trains themselves which are often better and roomier for those with physical disabilities.