> This is an artifact of the maximum complexity of front end apps having risen dramatically in recent years.

Front-end apps aren't more complex. Back in 2006-7 people were already writing complex front-end apps with frameworks like GWT or ext-js. What changed is front-end developers dropped the widget oriented frameworks for a lower level approach (stateless components). But the complexity of the apps have not risen.

You don't need IoC containers with javascript, it's useful but not mandatory. Angular2 tries to be some kind of kitchen sink of web frameworks but is losing its pragmatism in the process. I can guarantee that it will be drag its adoption speed.