Maybe it has to do with your job. I use my rMBP 4 cores heavily with editing 4K video and 36MP DSLR RAW images on the road. Both my CPU/GPU get the workout and routinely get 100% utilization. If your CPU load never stresses 25%, you would've been perfectly served with the 5 watt cpu in the rMB or the dual core on a 13" rMBP. Some of us have been wanting a quad in the 13" for years....
There are the few occasions where it does, i.e. gaming ...but day-to-day it rarely gets up there.
The point I'm trying to make is who really would notice a single digit percentage increase between broadwell and haswell.