How do I send a text? Messenger.
How do I make a call? Messenger.
How do I make a video call? Messenger.
Try answering the same question using Google's services.
Hangouts on my Nexus 6 has the same options.
Imgur link to screenshot -> http://imgur.com/a/vTlqO
This has understandably led to no end of confusion among Fi/Voice users, including myself. [2][3][4][5]
[0] http://www.techtimes.com/articles/128591/20160129/google-ret...
[1] https://support.google.com/fi/answer/6062495?p=fi_tips&rd=1&...
[2] https://productforums.google.com/forum/#!topic/project-fi/eg...
[3] https://productforums.google.com/forum/#!topic/project-fi/04...
[4] https://productforums.google.com/forum/#!topic/hangouts/AcKr...
[5] https://productforums.google.com/forum/#!topic/project-fi/cB...
The Pixel pushes you to use Allo which is based on phone numbers and your phone's contact list, not your Google account contacts. If I want to message someone on Hangouts but I only know their email address (which pops up helpfully if I have corresponded with this person in Gmail), no problem. You can't do that in Allo - the people you message are identified by their phone number, not the fact that they have a Google account. In fact, you can't use Allo until you register your own number. So what is Allo? Is it SMS? Hangouts could already handle SMS and Google also released Messenger intending it to be your phone's default SMS client. The only entity you can message in Allo that doesn't need a phone number is Google Assistant, which isn't that great. If Allo requires you to be identified by a phone number, how is it better than SMS? If I change my phone number, am I just hosed? The best thing about Hangouts is that it let you message damn near anyone in any manner while being platform independent.
(Disclosure: I work for Google, for three more days.)