From what I can tell, the Gmail add on just lets you create a new task from your inbox, but one of the perks of Asana is that you can post email to Conversations by using the team or project email address. For cases where you don’t have those email addresses memorized, it would be great to be able to find them - or just choose the team or project - without leaving Gmail. Right now, you’d have to go to Asana and lookup the email address you want to use before sending your email.
A workaround would be to create an alias in Gmail Contacts, for each impossible-to-remember firstname.lastname@example.org address, with an easy to remember name, typically the exact project name. Then you can just start typing the project name in your Gmail “To:” line and the correct address will pop up.
FYI I have a tool on my roadmap to get an export of CSV contact for any project you select.