What a load of...
"...the fact the tablet had to be tethered to a BlackBerry smartphone to use email..."
Gezus H... What a load of incomplete-to-the-point-of-being-perfectly-incorrect b... s... that is.
Any sensible email provider provides a web interface. These days, tying yourself to your ISP by using their email service ties you to their Internet access service - not smart. All major non-ISP email providers provide a web interface: perhaps you've heard of Gmail, Hotmail, etc.
Once you save the optimal shortcut then the webmail interface even allows access to attach files from almost anywhere in the PlayBook storage (something not even permitted by other OS choices). This so-called issue was a non-issue for many, thus proving that the statement as written is incorrect. We could "use email" just fine - even from Day 1.
And of course they eventually (these are the correct words...) provided a native email client app.
The initial omission affected some, but the statement implies a false impossibility.
Even today, I have never tethered to a BlackBerry phone since I don't have a BlackBerry phone. The webmail and the new email client app both work just fine through wifi (of course).
Please get your facts correct, and use the words that convey the correct facts.