The 'send' example perfectly illustrates why I would find Material 3 hard to use - it makes it harder to write the message but easier to send. It's less usable.
replies(5):
I am probably very used to the "old" design. If a user will use this product once or twice, yes then the big button at the bottom will be advantaged. But you are biasing the design for new users.
Existing users know exactly where the button is and will now have wasted space because of a gigantic send button.