It makes more sense to bust the pool in a year or two when their allotment is a lot smaller, if you're gonna bust, you have to do it in a big way to make it worthwhile.
Plus, the Phillies seem to have a really good pipeline to the "value" signings, they've found a lot of underpriced talent the last few years, that makes the cost of "busting" higher because outside of a few really high priced signings, most of these guys aren't going to be much more talented than the Francos and Kilomes of this world. Remember, for the most part we're talking 16 year old kids, unless they're uber talents they're far more risky than 18 year old American draft picks - so there's safety in numbers in spreading money around a lot of second and third tier guys.