They also allow flexibility of storing the password database, which I prefer over the services that store your passwords with them, as you are now reliant on their own security implementations. If you want to, you can store it in dropbox, so that you can access the web-based version anywhere you can log into the Dropbox website. You're now putting an awful lot of faith in the security of Dropbox, but it's an option at least.
But fundamentally, this is a problem which should be solved by the ecosystem providers. Windows, Mac OS X, Firefox syncing, Chrome (I assume Chrome has a way to sync passwords to wherever you're logged into, I don't use Chrome).
I'm comfortable enough trusting Apple to secure all my login credentials that I'm willing to use the built-in functionality. Much like how I use "Reading List" instead of any of the "article saver applications". It works fairly well, I don't have to mess with it, I don't have to give my data to some other company, it just shows up in all my browsers on all of my devices.