1) allowing poweful hardware to having mining advantage is simply against distributed consensus.
Even if BTC's algorithm was ASIC-resistant, the vast majority of miners would be people who could afford huge investments in mining equipment, particularly in expensive GPUs in areas with low electricity.
Myth: bitcoin does not have the drawback of fiat money - the total BTC number is 21 million.
The developers could change the codes tomorrow to allow 1000 million BTC in 2140
I assume that by "developers" you mean "Bitcoin Core developers", because it's important to note that a significant number of people run clients other than the reference client.
However, this is entirely false. If the Bitcoin Core client was altered in this way, people would have to choose to upgrade their client. If people still run clients which involve having a max of 21 million coins and they continue the chain with a max of 21 million coins, there will still be a max of 21 million coins.
But now, we have these "open source" central bankers deciding
on the money supply.
False. Central bankers decide on the money supply, whereas what Bitcoin Core developers do (not that they have any intention of doing this), is ask people to support an increased money supply. People could still choose to support the previous money supply and it would still exist.
Surely if the miners can choose how many Transactions to put into their block, there could be some kind of rule that says you must put at least 10,000 transactions in each block.
There is a maximum block size to prevent more transactions from becoming a burden to full node users. Miners are incentivised to reach the maximum block size with transaction fees.