For all its warts (which don't end up bothering me much), the fact that Hangouts' messages are available on my/any desktop, where I can communicate with a full keyboard, is a necessity for me. It's the chief reason why I've dismissed WhatsApp as a replacement.
(and since I don't use an iOS device or Mac, iMessage isn't an option either.)
If you want to make a webapp, fine, make a webapp and leave it in my browser like every other webapp. If you want to make a native client, make a native client. Don't do this half-assed crap that does nothing well.
But still the fact that I can use it on the desktop and the android client is pretty ok, makes me use it.
My parents-in-law still can't figure out how to get on their G+ account to use Hangouts, but for them Skype is second-nature. Open it, click on the contact, phone rings, presto, we're chatting.