From the standpoint of an overclocker, 7-10% more IPC may not seem like a HUGE boost, but that's not the end of the feature list for Haswell. IPC also isn't the only thing that strongly influences throughput.
The name of the game these days is power. TDP also doesn't say anything about dynamic performance during actual use.
There's quite a bit of misinformation in this thread about process and frequency.
I read the other day that intel uses a very poor 22nm process.
They claimed that Intels 22nm process didnt scale very well with voltage. 32nm voltage scaled up with performance & heat at a reasonable curve. The Intel 22nm heat goes off the scale very quickly and performance doesnt increase anywhere near the same way as 32nm. It was somthing to do with the type of process used. They said there are different processes which have shown to be far better for high mhz clocking.
This was actually discovered when they were trying to make certain A9 ARM cores run faster and a few companies hit nearly 3ghz with A9 cores where as the other process type would be limited at 1.7-1.9ghz
Intels 22nm process type is better for lower voltages at the same mhz as 32nm. But the problems come when you try and ramp up clock speed with voltage.
Link? Also, what does "poor" mean? If by poor you mean the process likely caters to the vast majority of the intended market, then I guess it's poor...
I know you were speaking specifically about overclocking, but that's a niche market. If a choice had to be made, and I'm not saying that it did, to pick between extremely high frequency and <insert any number of better reasons to go another way>, it should be obvious which one would be picked from a business point of view.