Although your general sentiment is something I agree with(if it's going to be painful do it and get it over with), I don't believe anybody knew or could've guessed what the reaction of the ecosystem would be.
Your last point about being able to change internals more freely is also great in theory but very difficult(if not impossible) to achieve in practice.
I don't know. Having maintained some small projects that were free and open source, I saw the hostility and entitlement that can come from that position. And those projects were a spec of dust next to something like Python. So I think the core team is doing the best they can. It was always going to be damned if you do, damned if you don't.
Since the switch we have seen enormous companies being built from scratch. There is no reason for anyone to be complaining about it being too hard to upgrade in 2026
It wasn't until much later (I would say 3.4 or 3.5?) that we had good tooling to allow for migrating from Python 2 to Python 3 gradually, which is what most tools needed to do.
The final thing that made Python upgrading easy was making a bunch of changes (along with stuff like six) so that you could write code that would run identically in Python 2 and Python 3. That lets you do refactors over time, little cleanups, and not have the huge "move to Python 3" commit.
The switch had nothing to do with Python's rise in popularity though, it was because of NumPy and later PyTorch being adopted by data scientist and later machine learning tasks that themselves became very popular. Python's popularity rose alongside those.
> There is no reason for anyone to be complaining about it being too hard to upgrade in 2026
The "complaints" are about unnecessary and pointless breakage, that was very difficult for many codebases to upgrade for years. That by now most of these codebases have been either abandoned, upgraded or decided to stick with Python2 until the end of time doesn't mean these pains didn't happen nor that the language's developers inflicting them to their users were a good idea because some largely unrelated external factors made the language popular several years later.
In case people have forgotten: python 3.3 through 3.5 (and 3.6 I think) each had to reintroduce something that was removed to make the upgrade easier. Jumping from 2.7 to 3.3 (or higher depending on what you needed) was the recommended route because of this, it was less work than going to 3.0, 3.1, or 3.2
Its widely regarded as a disaster for good reason, that forced some corrections in python to fix it. Just because its fine now, does not mean it was always fine
if sys.version_info.major == 2:
import old
else:
import new