Totally unofficial. I doubt we'll ever see official word on this type of question, to be honest.
The problem (-ish) of using the email model is that your Matrix connection is tied to your Lifestyle which can be tied to your SIN. From a design standpoint, that's something I try very hard to avoid. If your SIN gets burned and you have to ditch your cyberdeck license, that's one thing. If you have to ditch your cyberdeck, that's another.
I totally agree with the second part of your post, but I think that's still possible. A single persona could have multiple commcodes and check them all from a single device without a problem. You've been able to call your own phone to check voicemail for ages--that's such an antiquated way of doing things, I'm not actually sure you still can, but the basic design principle is the same. If I'm logged into the Matrix using my Joe Wageslave commlink, I can still check my messages on my Joe Shadowrunner commlink without a problem. It's just that the two devices have two distinct commcodes. Joe's persona is still the owner of both items, so you can use them no matter what avatar you're using at any given moment.
You never actually call Bishop's (my main character) commlinks; you call his router (essentially, a separate commlink that works like Grasshopper). The router then pings his PAN with an "incoming call" message. Based on who it is and what Bishop is doing, he'll answer the call with a different commlink. He has a totally clean router and a totally clean SIN that he keeps for recurring expenses and buys new routers every month or so for business use. Since he owns all these devices, he can see and interact them all without a problem.