Broadwell did have a better igp yes, but that's all it had going for it. They upgraded efficiency then gimped the clock speeds making it equal to haswell/d.c. The 4690k was stronger than the 5675c.
http://www.anandtech.com/bench/product/1261?vs=1500
Same with the 4790k and 5775c.
http://www.anandtech.com/bench/product/1260?vs=1501
No one with a haswell i5 or i7 would have bothered with the broadwell sidegrade. Now if someone were coming from an older cpu and upgraded to a new i5 or whatever and that happened to be broadwell then sure. But not from the previous gen. Same with the 2nd to 3rd gen, unless the upgrade was from an i3/i5 to an i7 those sticking with the same cpu (say an i5) and upgrading simply to go from a 2nd to 3rd gen were burning money to get a sidegrade. It's always been this way.
Those with a 2500k saw no reason to jump on a 3570k, most didn't bother with a 4670k, 5675c and are now considering the 6600k as a worthwhile upgrade. They skipped an entire socket and 2 gens (with a refresh) with no trouble. Same will happen with skylake, kabylake, cannonlake. Unless intel comes up with some serious magic which I highly doubt. Things are getting tougher at smaller die sizes not easier. If going from 22nm to 14nm was a pain, wait until 10nm or 7nm.
Even if broadwell hadn't been delayed it was more or less an efficiency bump with no performance gains. The best thing it had going for it was the mobile market due to the improved igpu. Intel didn't even want to release broadwell to desktop, the improved igpu and lower power requirements were mobile perks. Most people are using dedicated gpu's anyway which still smoke even broadwell integrated graphics.