Not really worth the extra $50-$100 vendors were charging, and the i3 was a better value (the fact that Apple doesn't offer an i3 laptop was a big tip-off where the fat profit margins were). Prior to Haswell, the turbo boost on most of the i5 line was pretty modest - about 5%-15% base clock speed. The i3 has 2 physical cores, hyperthreading, and no turbo boost.
The i5 has 2 physical cores, hyperthreading, and turbo boost. Broadwell just has lower power consumption, which you don't really care about on a desktop. So unless you're going to use the integrated GPU extensively, there is virtually no performance difference between the two generations. On top of that Broadwell (5th gen) is just a die shrink of Haswell (4th gen). The i3 has 2 physical cores, hyperthreading, and turbo boost.
The i5 has 4 physical cores, no hyperthreading, and turbo boost. There are a few things that i5's will always be much better at doing such as hyper threading and turbo boost. CPUs don't REALLY get obsolete that fast.
