Agreed. Filling up my pitiful .5gb of space with repeated imbedded images is not something I appreciate.

On a desktop, one can use keyboard shortcut Ctrl+A and start typing a reply.

Agree with one possible refinement: when in an email conversation with multiple emails and replies going back and forth the whole previous conversation is included. It would be helpful to (optionally?) only include the last reply.
This would also solve another issue: currently, when opening the previous replies to an email the whole tree is expanded, which can be extremely long.

Implement a feature that allows users to reply to an email without including the quoted text of the existing conversation. This option should enable users to send a clean response without the need to manually delete the quoted content.

This is a must in some cases. Some people have ridiculously long signatures, and when you have a thread with multiple people like that, it gets obnoxious because it is so easy to get lost.

Via the web you can delete individual emails in conversations, but not on a smartphone

TOTALLY agreed!!! Sometimes I want to keep it, sometimes I don't, so some kind of checkbox in the reply window would be fantastic. With the beta it seems like you have to click the button to expand, then try to delete it all, which is not efficient and annoying. If nothing else, at least in Gmail, when you press down, it highlights the expansion button and you can press delete.

Agreed. How annoying

Just a simple button to remove all the previous conversation from the current reply/message/forward and/or an other button at the top to offer the opportunity to reply without quoting original.
There are many situations where you do not want to keep the whole history included, after a few exchanges back and forth it can get pretty messy.