It looks like the 8% dev tax for bitcoin cash is going to be implemented, do you guys think this is a good idea to also be brought to BTC as well in order to have funds for future development instead of relying on donations?
Bitcoin has many developers and volunteer working around it. Everyone can freely propose any update they want.
Adding a feature like a "dev tax" where the fees goes to one entity and address then there would be some concerns about centralisation and we would also give this specific dev with the address, in my opinion, the right to call himself the "CEO of Bitcoin" or "Satoshi" because he gets the dev fees. Of course this sounds a little dumb because we all would know what this is but imagine a newcomer comes in and finds out that address and then claims to found the real "satoshi" because the dev fee goes to a developers address and many would think that this was implemented by Satoshi himself.
I could count many more reasons why this would be a bad idea but I hope you get it that this is just not good for bitcoin and decentralisation in general.