I use the auto-generate password feature of Lastpass every time I make a new account. A problem that I encounter, I'd say 50% of the time, is that the button is adjacent or conflicting with the "reveal" button on many websites (depicted below on the right side).
This makes the auto-generate button not clickable, so I have to go in the extension and generate a password that way.
One suggestion would be to make the auto-generate option on the left side of the password field, or at least move it to the left 50 pixels or so, so it doesn't conflict with the "reveal" button baked into many password fields.