I will need to play more of silksong to be able to comment fully, but I felt that, even though you could understandably say all the same stuff about Hollow Knight, I still do think that the only times I struggled in HK (on required content) I later found out about an upgrade that was available if i had looked that would have made the fight much easier (nail upgrade, ability, charm, more hp, etc).

No, not to the same degree as Elden Ring, i agree, but I do think HK's exploration played a very similar role as it did in Elden Ring. In both games i would tell people to only bash your head against a boss if you want to hurt yourself, otherwise go explore.

Do you believe DS and Megaman could have been even more iconic if they had listened to players and made their runs back shorter?

My point is, it's not like the designers didn't know what they were doing, this is a very obvious aspect of their gameplay. And regardless of how minor inconveniences like this make us feel as players, we don't know that it's not precisely those lows that contrast with the highs to create the intended experiences which made those games cult hits to begin with. You wouldn't look at a Rembrandt and say, "look how much of the painting is just black! You're wasting all this space! You could add so much detail and context in there!"

I'm a firm believer that "given the opportunity, players will optimize the fun out of a game". If players weren't complaining about the run back, then they would be complaining about the empty flask drinking animation. Inconvenience is not a convincing argument to me. Just like any art, games are free to evoke any and all emotions. It only becomes a problem if the emotion they keep evoking is boredom lol. But even then, boredom is a valid tool on the artist's palette; sometimes the only ones who are getting bored are the boring people.