For me it’s scalability and privacy that bitcoin lacks.
To me I was always of the belief that these features would be added to bitcoin eventually at least that was a narrative by bitcoiners a few years ago.
When someone says btc should not change then I get the feeling. They are saying just use ETH or Monero instead. Btc layer twos should replace the need of these altcoins. I don’t like these the way these coins were created at all.
I agree what makes btc unique is the fact it’s difficult to change. But if we want bitcoin to scale to 8 billion users then we need to make small changes. Bip300 would be the last ever change needed to bitcoin to ossification imo.
This is just my opinion. Everyone has their own desires of what they want bitcoin to be. This is just my take.