I'd maybe do one project like this for a top tier company, but most companies that do this are limiting themselves to the already unemployed who have the time, if you want to pull people from other companies you need to minimize their time investment. Remember it's not just a 4 hour project, it's 4 hours * the number of companies applied to. I'd also argue that you can't show off things like architecture and design patterns in such a short project, all you can show is that you're over engineering.

I've also been burned before, getting dinged for "not practicing TDD because the tests and fixes are in the same commit", there can be just as much arbitrary BS as a simple short code test.