Because the standards, as yet, are incomplete.
So far just the protocol and the USB implementation are there.
There is, for instance, no MIDI 2 file specification.
You can't recode a sequencer (DAW) unless you know how the messages need to be stored.
I don't recall reading anything that says that Steinberg's VST specification has been updated to include MIDI 2 messages either.
Standards as important as these take their time to define and implement, just like telecom ones.
It's quite possible that many manufacturers have deemed that the new messages are too complex for most commercial products.
They may end up only in top end devices.
It's a massive job too, to rewrite thousands of lines of code to incorporate all the changes.
Yes, we do need support from the major OS companies in an updated MIDI API. That is happening but it is a big task. Everything from the underlying data format needs to be updated. Class compliant drivers for USB are a small part of that. Even with those drivers, the new transports cannot be used without the updated MIDI API. After we have an updated API then DAW companies can implement. Covid19 has slowed progress considerably. I think we will see the first batch of early adopter MIDI 2.0 products later this year.