We use G Suite because of its cheap costs, easy management/administration, Excellent DKIM score, and everything that comes with it. We switched from Microsoft Office 365 because it doesn't work on Linux which is our OS of choice. Furthermore, G Suite does not lack any of the features that Office365 had to offer, I'd even say it offers more.
I've worked with both G-Suite and 365 and I'm inclined to agree with you, with some minor exceptions around mail handling.
I as clients of mine have been blown away by the performance of GSuite, some of them have saved thousands of dollars because they cut down on hardware they had to buy (from i5 to i3 saves around 200euro's per machine), the license costs, and in-time the savings over the years could add up to the millions because it's really easy to integrate scripts with online spreadsheets. Which saves countless hours of work.
When I worked at Trimble Navigation, they saved over 1MM a year by switching. I would love my company switch, but it's a really hard sell in spite of the better API, lower cost and better choices on ancillary tools/products