Clocking them down is not stealing from CPU performance? Your own quote contradicts what you're saying.
Sigh. If you'd read the article, you'd understand why your statement makes no sense. Tom's Hardware goes on to note that Broadwell is ~5% faster than Haswell at the same clock speed. The reason Broadwell shows slightly lower performance on some benchmarks is that it's capable of dropping down to lower clock speeds to conserve power. But when performance is called for, Broadwell quickly ramps up to the same clock speed as it's predecessor. So for a sustained workload, Broadwell will be faster. It's only for those loads that frequently ramp up and down that Haswell comes out ahead.
So nothing is "stolen" from the CPU. Most of the extra gates proved by the 14nm process in which Broadwell is fabricated are used to enhance the GPU, which as noted by the reviews is now the fastest integrated graphics unit on the market. But nothing was taken from the CPU -- in fact, the CPU is enhanced to be 5% faster on a per clock basis and to also drop to lower frequencies when *idle*. If saving power isn't your thing you can always disable power features through either the bios or the O/S to keep the CPU at higher frequencies most of the time.
Dropping the CPU frequency to lower values when cores are inactive is an important feature in all modern CPUs. Many server customers care more about performance per watt than they do about raw performance. For laptops and handhelds, efficiency is critical. And even for desktops it's a nice feature.