Touching the screen and touching the phone are different. Ok, its cool that the Moto X is always listening. But whats the point when you are required to touch the screen to confirm actions? At least on the iPhone you have a physical button to invoke Siri. You never have to look at your device.
If you are driving and need to send a text to your significant other without taking your eyes off the road, you can do it with Siri, you can't with Google Now. Or if you are running and have a headset in, you can create calendar events with Siri, you can't with Google Now. Maybe you are laying in bed and you don't want the bright screen to shine on your eyes but you need to set a reminder. You can do that with Siri, but not Google now.
Sure, always listening is a cool feature. But it is crippled by Google Now. Implement always listening with a personal assistant that actually allows you to perform actions by voice and it would really take it one step further. The Moto X doesn't really move you one step forward towards hands free operation thanks to Google Now requiring touch input. At most, it takes you a step forward on a treadmill. In an ideal world, the always listening feature would be on iPhones and Siris ability to not require touch input for voice actions would be implemented into Google Now. They both have flaws. But with my usage, having a physical home button you can touch without ever looking at your phone and doing all actions by voice easily beats the no physical button and requiring touch input.
I think as long as Google now remains unchanged things like voice activation are just polishing a turd IMO.