Why do you say that anything but toy and demo NEED concurrent indexes? So far I have built toys and demos and never needed concurrent indexes, are they a must to dramatically speed up production workloads or am I missing something?
You'll be fighting tooth and nail against anything larger then a row level lock if you're targeting the consumer internet and allow user generated data/user writes.
you'll probably never care if that's not the case, which is arguably the usual situation. Even b2c Websites often don't have user generated content to speak of, so they're pretty much just talking from a bubble (I do get where they're coming from, I couldnt have done them either at some of my previous employers)
This is a non-issue on things that don't have real traffic going to them, or on small enough tables that the indexing time is trivial.