That is all way blown out of proportion.
The bladesinger and maybe also the eldritch knight a little bit were hit by the sloppily designed bladesinger cantrips.
Both characters now had an ability that played poorly with GFB and BB as they were designed. Probably the best idea would have been completely redesign the cantrips and make them like at will variants of the smite spells. Cast on bonus action and unleash on next weapon attack. That would make them play well with both classes.
They now changed the extra attack from the bladesinger to be special, so that they can encorporate any cantrip. Probably they redesigned the eldritch knight feature to just upgrade extra attack to the bladesinger variant.
The game is actually hurt more by not updating sloppily designed spells and classes. Since the bladesinger is from a comparably unsuccessful supplement, updating the core seems a good idea.
The ranger didn't have the same luck.
Whirlwind attack and TWF don't work well together, actually Rangers have a lot of conflicts with their bonus action so better not use TWF in most cases.
Because for now the PHB is so holy to remain mainly untouched the Ranger gets a few alternate features as a patch.
Wait 3 years, and we will get the full upgrade to the PHB.
Your mentality to never ever upgrade can be compared to software developers refusing to update their system, because they fear to lose older uses, but they ignore that younger uses are used to much better developed systems and at some point have to notice that a newer contender has taken over the market.
You're misrepresenting my position, though I am not sure if it's intentional or just poor phrasing on my part.
I am not saying "never upgrade." At all, in any way. If that was implied by what I wrote, it's a mistake on my part and not my position.
I am saying all of the following:
1) don't use stealth errata to upgrade, use the errata which is the expected way to introduce errata,
2) make errata timely in nature, and do not wait 5 years if it's a known issue,
3) don't errata things which nobody was complaining about or which was a known real issue,
4) if you need to errata because of some new content you're creating, do it in a more elegant way that doesn't mess with older content such that existing players will suddenly feel like their characters are retroactively out of date.
IF this errata is so that new versions of classes can use these cantrips, then PUT THAT IN THE NEW CLASS. Or phrase the errata in such a way that those classes can use the cantrips while old characters outside of those classes can still use them the way they were previously using them. I am betting that's possible. In fact you're a pretty good rules-tinkerer yourself, and I bet you could have phrased these to be compatible with a an older existing class who just had the feat to make opportunity attacks with a cantrip, AND still be compatible with these new class versions, in a way that doesn't break anything.