1. Do you want large institutional financial organisations buying large amounts of bitcoins and then locking it up in centralized trading platforms?
Why not exactly? You can't stop anyone from buying bitcoins. If you could, it wouldn't be trustless and censorship-free, meaning it would lose its most important feature.
And if we don't have any control over who is buying it, there's no point of asking such question.
Plus, with large financial institutions buying it, there's less risk of it getting banned.
2. Do you want Bitcoin to be a commodity or a currency? ETFs will destroy the goal of Bitcoin becoming a currency.
Are there actually any developers out there trying to make it useful as a means of payment? Looks like the lightning network is all we have, but it's far from perfection. It seems like the "community" (whatever that means) quietly accepted Bitcoin becoming mostly a speculative instrument.
5. ETFs destroy pseudo anonymity, because it is highly regulated with strict KYC requirements implemented to identify every trader on their platform.
I think you mean "pseudonymity". Yeah, this is probably the main threat. When most investors choose to hold ETFs rather than real bitcoins, there's a greater risk of regulators pushing for delegalisation of any non-KYC wallets and other services.