I just noticed today the Send button is no longer incorporated into the IDE 2.0 (Version: 2.0.0-beta.7) serial monitor (at least for the MAC version)
The keyboard shortcut is also less terse now (CMD + return vs just return on the old IDE)... but I also think the Send button is a good visual indicator of how to send data.
I know the help text is right in the send box, but it goes away once you type something and you're left searching for a button to send the values.
I would like if the button were still there. Just my two cents