I understand people want Junior jobs to exist, as junior developers. As someone hiring, why should I hire one? Serious question...
1. You have no trouble hiring senior developers whenever you need one
2. You have no shortage of money to pay them
3. You are running a short term business, so your time horizon is only a year or so
4. You have no work that has been put aside as high risk given the uncertain benefits
5. You dev team is fragile, and liable to be gummed up
Then by all means do not hire junior people.
But if any of those do not apply, you will find all sorts of advantages. Look at the Google Summer of Code as a model, say. You get enthusiastic people willing to learn, who you can teach your way of doing things, and fast track their dev skills so they become senior sooner. So long as your codebase is slightly modular there must be something people can start on, and do not forget that teaching is a great way to help you think about things in more detail, and that meta thinking is the most important way in which you become a better programmer.
Cheap but enthusiastic (and perhaps plentiful) labour, who may be able to work on non-critical path items, and there may be ancillary learning benefits from mentoring to existing senior devs.
Is that about the size of what you were saying?
Young/junior developers often have a lot of spirit and enthusiasm which is injected into an existing team. They'll also tend to bring the 'latest new ideas' which while not already ideal does get the old guard thinking. If anything it's interesting to watch people adjust their proverbial footing to stay relevant.
On a similar note, I often wonder how does a senior/lead developer take a different direction? I took the JVM + Web stack and I was giving it serious thought to jumping ship into another area of software development. Now understandably you wouldn't be a lead but rather a born-again junior yet any interviewer will automatically assume (with evidence to the direct contrary) you've been doing it for years.
Tricky our industry...
You might decide that your business can derive a significant amount of experience from people who don't have a computer science degree. Those people might be easier and cheaper to hire. So it might be worth hiring them.
Fundamentally, the question is whether the hire is worth more to the company than the cost of employing them. If you think that CS graduates with four years of experience are overvalued by the employment market, it's a good move.