I think when we are using these sites and tools with kids, we need to mindful of safety, privacy and district support. Can you create sites other than what the district recommends? Probably, but you are doing so without that support. For example my class' wiki each year isn't supported, but I'm mindful, about the privacy and security and get parents to support. You will not see anything unless you've been invited or request permission.
I don't know, for me it just seems like it is a no-brainer now that we will have these great tools and support behind them (apps is a complete blanket of privacy, no outside sharing and all docs, sites, and more are under one umbrella)
Keep pushing the thinking, and be mindful of what the goal is. If the goal is teaching 21st century skills and fluency in tech literacy then a tool where the students are the creators, editors, and collaborators seems the most beneficial.