The absence of a need for mining gear presents with a problem as there is no other provable backing for fiat currencies besides trust in the system. The gold standard used couple of years ago served as a means of backing up currencies by real value and was adopted by many countries, but has long been dropped.
Bitcoin's algorithm offers such proof of value while still being environmentally friendly. I would call that an improvement.
PoW doesn't not back Bitcoin's value, it's only goal is to make the network actually work, so that blocks can be organized in sequence. Bitcoin's value is purely speculative, which is why it's so volatile. You can't just burn a ton of electricity to produce something and then claim that it's backed by all that electricity so it's now worth something.
I doubt the ability of Bitcoin to scale up to certain levels, but it is a growing technology with lots of room for improvements, so I wouldn't want to nip it in the bud. A couple of BIPs aimed at improving scalability has already been implemented and some like Schnorr and Taproot are yet to be.
Certainly a lot of improvements will be made, and I don't want this to divert into a scalability debate, I'm just saying that for now and for the foreseeable future Bitcoin is nowhere near close to have the same capacity as the payment networks that are used now.