Hello Merle, 

I am happy to get this escalated as a feature request for you. In the mean time you can use a work around. You can create templates using your signature. 

Go to settings -> signatures here you can create a new signature as a draft message. Start a new message and in the top right you can select the signature that you want to use. Once this is set you can click the "Unlock Signature" option in the compose window to edit the draft/signature and send.