That isn't actually a problem, since you sync (back up) your phone to your computer. If something happens to the phone, you just restore your data to a new phone. If your computer is a Mac, most likely you're backing all your data up, including the sync data, to an external/network drive.
At least for the iPhone, if you lose it or it's stolen, you can locate it via GPS, and/or remotely wipe and brick it. The default protection is a four digit PIN, but you can only try to guess it a few times before the phone locks you out for increasingly long timeouts.
I use a five digit PIN, makes it really hard to guess. When my device was lost last year, I remotely wiped it. Luckily for me, the person who took it turned it in after a week as it was useless empty as a brick. Restored it via my Macbook in a couple minutes.