yeah, they limited their market for sure by doing that, but from what i read the reason they did that is for security reasons. the blackberries are already bulletproof in the way of email security, and because the playbook is on a different os they couldn't guarantee the same level of security for it by launch date (which was already pushed back several times), so bridging the phone's security over to the tablet was the way to go for them.
that's how playbooks are now standard issue for government officials in the states and i think russia or something like that. i think local law enforcement are using them too or something.
os2 promises to have native email and calendar clients, but i still think it's a little too late.
having said all that, i love how my playbook bridges to my phone, i find it annoying having to check all my emails over 3 devices (home computer, work computer, phone) when i've read the message already. with the playbook paired to my phone, i don't have to worry about reading it yet another time.