I don't use Messenger myself, but I can see how this is a strategic move and may increase the appeal of Facebook Messenger.
Today, we’re introducing video calling in Messenger. Now you can have face-to-face conversations with your friends and the people you care about, via Messenger. Facebook Messenger Now Has Video Calling [newsroom.fb.com]
bill
12:24 am on Apr 29, 2015 (gmt 0)
I may be one of the few who refused to install the separate Messenger app on my phone. When someone sends me a message on FB they can wait until I bother to check in, which isn't often. Video calling on that platform doesn't appeal to me at all while there are newer, more secure ways to do the same thing. Despite my reticence I'm sure this will be a huge success for them.
engine
12:45 pm on Apr 29, 2015 (gmt 0)
I'm with you - i didn't install messenger on my phone, despite all the nagging by FB.