When I'm getting ready in the morning, I will rarely check the weather on my phone because first, I need to find my phone (I seem to put it in a different place every morning) and then I need to click multiple times to see the information I want. With Echo, I can say "Alexa, will it rain today?" or "Alexa, what's the temperature?" and get an answer instantly while I'm doing other tasks. It might be less useful for smart watch users that wear them 24/7 (I don't own one).
This is very true. With Google, you have to say "Ok, Google", wait for it to go "bleep" and start listening, and only then ask.
With Echo, you just say "Alexa, what time is it" in a single second, and you get your reply.
In crowded settings, or sitting still, I will almost always just grab my phone before having to worry about whether or not the environment is too loud, which is (I suspect) why you probably see so few people using it.
Beyond that, I agree that verbal commands on a bus would be inconsiderate both to the other passengers as well as the recipient of the message, whose privacy I just (slightly) violated. That said, if I'm sitting on a bus, I don't really have a good excuse for not typing the message myself, and typing is still slightly preferred except for when my hands are occupied or my phone is not conveniently accessible.
Maybe I have the wrong circle of friends and acquaintances, but I have never ever seen anybody interact with Siri or Google Now by voice other than as a demonstration or a joke in social settings.
I love my Google Now, I love even more that it does not shout things at me when I am in the bus.