These chips look better suited to servers than clients as is. Most software still scales poorly with additional cores (or rather: most workloads still have a few single-core bottlenecks). E.g webbrowsers, compilers, video de and en-coders, all kinds of stuff. So even if you have twice the cores, catching up given the handicap of a single-core perf disadvantage is a pretty harsh battle.
E.g. see http://www.anandtech.com/bench/product/1826?vs=1729 (6900k vs. 7700k) - there are quite a few relevant workloads where the 8 core loses significantly to the 4-core. Even stuff where you'd think more cores are really natural (such as POV-ray), the perf advantage of the 8-core over the 4-core is less than 50% (!). For an example where fewer faster cores obviously win, consider web-browsers: the 4-core is 36% faster in google octane v2.
Servers that have lots of independant tasks, on the other hand, will love this cheap many-cores. And coincidentally, servers often don't use AVX all that much anyhow.
Of course, fewer cores usually means a higher available clock speed. Just pointing out it's not just "code isn't parallel enough" that drives the disparity.
Sure, the 8-core runs at a lower clock speed and and old arch - that's a major (but unavoidable) part of the problem, as I said.
To be specific: you can't get the equivalent of a 7700k with eight cores - the 6900k is (AFAIK) the next best thing, and by the looks of it, ryzen for all it's revolutionary improvements wrt bulldozer, is not all that different from a 6900k. AMD's own numbers place it at an identical single core perf.
I have a 5820K (6 core 3.3 ghz base) and using Handbrake to encode a HD .mkv file from MakeMKV, the 6 core machine beat the 7700k clocked at 4.2ghz. Once I overclocked the 5820k to 4Ghz, it was about 10-15% faster than the 7700k which I had then clocked to 4.6Ghz. So I'm looking forward to the 1700x. Not all programs scale as well as Handbrake does with more cores.
Sure, there are situations in which it's faster. In my (limited) experience with x264 at least the more extreme quality settings didn't scale quite as well, and those are the only ones I use. Regardless: some programs parallelize quite well, others not so much.
If you're lucky enough to primarily be bottlenecked on parallel stuff: go nuts, of course!
In any case, I don't want to suggest I'm not happy with AMD finally being a real competitor, I'm just trying to temper expectations of intel-beating world domination. Most users aren't so lucky. Many people use laptops, and slow websites are more of a problem than slow handbrake sessions. For me, it's visual studio and various build/run cycles. Sure, some tools use more cores with the right settings, but it typically scales really disappointingly after around 2 or so. That overclocked 5820K would probably lose to a stock 7700k in my workload, and that's just annoying.
E.g. see http://www.anandtech.com/bench/product/1826?vs=1729 (6900k vs. 7700k) - there are quite a few relevant workloads where the 8 core loses significantly to the 4-core. Even stuff where you'd think more cores are really natural (such as POV-ray), the perf advantage of the 8-core over the 4-core is less than 50% (!). For an example where fewer faster cores obviously win, consider web-browsers: the 4-core is 36% faster in google octane v2.
Servers that have lots of independant tasks, on the other hand, will love this cheap many-cores. And coincidentally, servers often don't use AVX all that much anyhow.