Mistwell, all of these examples involve prior scouting, encountering a problem and then being able to take a Long Rest to swap out spells.
That is not always possible. If the mechanical dragon is enroute to burn Ten Towns, the PCs don't have time to Rest.
Again, THAT'S THE WIZARD THING. Of course it involves a rest to swap spells to do those plans! It's what the Wizard has done in almost every edition! That's their Schick! Nobody PREPARES the Knock spell (it doesn't come up often enough to require a precious spell slot prep in unknown danger situations). It's on the list to do just what I described - prep it when you see the need and you have time to come back to it. Same as most of the other highly situational exploration spells.
As it stands now, the Sorcerer or Bard in the examples you gave are only able to help out,
if they happened to have the correct spell. Otherwise the player is helpless until they gain a level and can swap spells.
Exactly. It was the Wizard's thing, exclusively. It was one of their defining features. It's why countless threads have called them the swiss army knife of spellcasters. Did you never wonder why people called them that? I am glad we're all caught up on what the Wizard had before and the sorcerer and bard did not, and how this change gives away the thing the wizard had. We're on the same page now, finally.
If you only play only once a month, that could be a really long time to expect a player to do nothing.
Games involving a lot of downtime, or time to plan and prep, favor Wizards as is.
It only favored the wizard for the reason we are discussing. It now favors the sorcerer, because they now get all their spells while the wizard is only guaranteed 44 over the course of 20 levels.
As a DM and a player, I am happy to have anything added that helps groups overcome challenges. The sorcerer can now call upon their dragon ancestors and learn the magic words of opening to the sealed portal...cool!
You as a DM always had the power to deal with the situations you threw at the players. That's a horrible excuse for altering the classes this much. It is, again, the idea of giving the unarmed fighter to a ranger or the wildshaping to the paladin. Why they heck would you, as the DM, throw a door at the players they couldn't unlock without a knock spell? The purpose of that example is to let a wizard shine, if the DM know they have Knock in their spellbook that they've never used. Otherwise you could have given a key. Or no super-locked door to begin with!
Again, if your neighbor gets a raise, this does not make you poorer, especially when they are in your D&D party.
I am going to bludgeon you with this silly myth until you grok it. Nobody is arguing the sorcerer should not get a raise. People, including me, are arguing they should not get THIS KIND OF RAISE. Because THIS KIND OF RAISE does in fact make another class poorer. In the same way making a sorcerer a better wildshaper than a druid would in fact make the druid player feel like their special spotlight niche in the game has now become more mundane in nature. I know you get this. Why do you keep repeating this silly platitude you know doesn't match this situation?
You're not giving them a "sorcerer" raise. You're not, for example, giving them more points to gain more metamagic uses (which I favor). You're giving them someone else's special thing and for a bad reason. Nobody was running around and saying the sorcerer needed to be a better swiss army knife spellcaster than the wizard! They needed a boost to being more sorcerer! Not to being more wizard-like. We already have a wizard class for that. That's the purpose of class identities - to make them distinct niches in the game from each other. With this new rule, there isn't really meaningful identity to the wizard. A sorcerer with the ritual caster feat is a better wizard now, because they also get all that metamagic and other sorcerer abilities.