Default [Q] Google Now Drawbacks?

I'm really into the functionality of Siri, S-Voice and Google Now. I find it curious that Siri has a couple of advantages over Google Now in as much as it can be accessed and used from the lockscreen of a password protected device (only asking for the password when necessary) and that it also uses Wolfram Alpha's knowledge base.

Now, I'm guessing the lack of Wolfram integration is simply down to negotiation. But I'm confused as to the lack of access on the lock screen. This might seems minor, but it greatly reduces its perceived usefulness and slows down interaction. Any ideas why this hasn't been implemented yet? And will this be coming in future updates?