We can imagine that micro-USB got standardized in 2015, so in anticipation of that the first USB-C phone I bought that year came with micro-USB instead.

The law would then have been reassessed in 2020, at which point some EU bureaucrats would have had to weigh "reversible connector" etc. on one hand, and "take the career fall for forcing half a billion people to buy new chargers" on the other.

If the law had been passed in 2015, they probably would have picked USB-C as the newly finalized, and increasingly adopted, standard. Micro had already started to show its flaws by that point. Also, it's not like everyone in the EU needs to buy a new charger overnight; plenty of people would have a while before their next replacement, and plenty of others would have already gotten some other peripheral with the new port.

I can buy that, but I also think that we're now much less likely to replace USB-C, even if the reasons to do so in the future are just as compelling as the reasons for migrating away from micro.

Actually, I think (but I'm no lawyer) that if the USB-IF wants to standardize a new connector, they'd want to call it USB-C v2.0.

The law seems to implicitly defer to them to define "USB-C". If the consortium wants a new standard they could either reuse the name, or wait 2.5 years on average for EU approval or rejection.