So do I understand that the addresses can't be added to the gmail app itself?
( Apologies for hijack)
I guess I'm confused. The email app is for reading and composing email. The people app is for managing contacts. The two apps interoperate seamlessly, but they are separate apps that perform separate tasks.
If you want to send an email to someone, you can do it one of two ways:
1. Look them up in "people" and tap on their email address - Gmail will open with an email pre-addressed to the person. Type your subject and whatnot and hit send.
2. Go into Gmail and click the "compose email" button (envelope with plus). In the TO: box, just start typing the person's name or email address and it will search your contacts and find matches. Pick the match you want, then type your subject and body and hit send.
Other apps use your contacts as well, like the "Talk" app (IM, audio, and video chat with other Google users), Google Voice (if you have it installed), Google Plus, etc etc.