Do shipping containers make good homes? They're hard to cut, hard to insulate, have little structural strength, and generally end up using framing lumber and other traditional materials to make the dark and cramped interior livable. They are, in effect, a trendy cladding material that you build a real home inside.
Sixth issue: the idea that you are saving the environment when you use shipping containers and that is a highly sustainable practice. Another important thing to consider is the carbon footprint of your container home. Steel construction is not as environmentally friendly as wood.
Seventh issue: the idea that shipping containers can be the solution to the housing crisis in the world but, this crisis is not a technology problem, it's far more complex. Purely from a financial aspect, it would be cheaper to build a homeless shelter with wood than build a complex shipping container building. This type of building can maybe be 20% cheaper, not more. The modifications that you need to make a metal box livable aren't cheap.
There are, of course, other perspectives.