It seems like someone said, "why don't we have a WhatsApp competitor?" and so Bob and Steve made it without thinking about all the different messaging applications already under the Google brand.
Pretty much. Which, on its own, isn't a bad thing. A lot of innovation can happen that way. But see Wave, Talk, Hangouts, Spaces, Allo, G+ [0]: Many communication apps, some mobile, some defunct. They've each added something, they've each lost something.
G+ introduced "Circles". I really liked that concept, it was a smooth way to organize the people I wanted to communicate with. Post a message, only my gaming buddies could see it. Post another, friends and family (and most gaming buddies fell under friends) could see it. And it was under my control and invisible to other users.
Talk: Adds nothing, it's just another messenger.
Hangouts: ... video and audio chat. Screen sharing.
Spaces: Seems like a more socially oriented Wave?
Wave: Neat, got stuck in performance hell and was hard to sell. The invite system didn't help. Collaborative documents. Integrated chat bots with the document much like this @google thing in Allo seems to be.
Allo: Talk - gmail account + (end-to-end encryption OR @google chatbot). It's WhatsApp meets part of Wave meets Google Talk.
Take G+, integrate Spaces into that. Make Hangouts part of that. Make Allo a part of Hangouts. Move Hangouts to end-to-end encryption model (broken with @google chatbot present, but not if you leave it out).
[0] I'm excluding GMail because it, at least, has a fairly well established place on its own and is, fundamentally, an email platform. The accounts are tied to the other services, but GMail is easily its own standalone product with a very large user base.
I just wished that they hadn't killed Talk on mobile. I had converted all of my friends from AIM/MSN to Talk, but that was the last time everyone actually used the same messaging system. Now people use Skype/Facebook/Talk/SMS/Snapchat/??? whatever the new fad is, a few breakaway and use it.
