No one calls a tablet a computer. No sane person expects a tablet (key point of tablets: Mobile) to perform like the more conventional / less mobile computers
If you've never had a laptop throttle and/or overheat, you're either very young (I think you are) or very lucky.
If you don't think running up against a tablet's specs is niche, I suggest you take a course in statistics.
I've been using PCs since DOS 3.x and the only times I've have a laptop throttle to 50% of its normal performance was:
A) When the laptop's cooling design was obviously inadequate (the one Dell Inspiron I had like this was returned, similar to my former SP3 i5/256gb)
B) When the laptop was used improperly (vent covers blocked, or placed on a rug)
C) When the laptop was broken
I have not had a well designed laptop throttle as significantly as SP3, and I think it is poor engineering to depend on the CPU's throttling to 50% of its normal performance like Surface Pro 3 as a "cooling solution."
I do understand people are excited about the SP3's form factor, but I see far too much excuse making due to that excitement in my opinion; there is very simple logic here that cannot be evaded:
1. If the argument is that a tablet cannot perform like a laptop... this is false as proved by the Surface Pro 2 Tablet with same i5-4300u CPU, which did perform like a laptop; Surface Pro 3's cooling solution is inadequate for the CPUs Microsoft selected - this results in severe throttling that was not present even remotely close to this extent with the same i5-4300u CPU on the older Surface Pro 2. The Surface Pro 2 offered consistent performance, unlike the Surface Pro 3.
2. If the argument is that the thinner design of SP3 (vs SP2) is a tradeoff that results in it being simply impossible to cool Haswell Ultrabook CPUs like SP2 did... then why is Microsoft offering these CPUs with SP3? There were other x86 options available at the time SP3 was launched such as Intel Atom Bay Trail, and Microsoft could have launched with MSRP $699 Intel Atom Bay Trail 64gb/4gb, $849 i3 Haswell 128gb/4gb, and $999 i3 Haswell 128gb/8gb - the latter for those that use a slightly intensive application like Photoshop. Then, later this year add MSRP $1299+ i5/i7 Broadwell 256-512gb/8gb designs for those that need more performance, as Broadwell will likely run efficient/cool enough for SP3 to manage without extreme throttling. You know, instead of charging people for mid/high end i5/i7 CPUs that only work for a few minutes before throttling to the speed of a low end CPU; while I appreciate marketing and capitalism, this practice just seems a bit dishonest.
3. If the argument is SP3 is not as good as a laptop but good enough given the form factor... I do appreciate that the current SP3 design works fine for some, but I do not see how these same individuals would not be similarly served by an i3 or even a Atom Bay Trail processor. An Intel Atom Bay Trail can handle everything available in the Windows 8 Store as well as Office perfectly fine, and if you want to go a step further with something a bit more intensive like Photoshop the i3 works great for this. If your programs are not CPU hungry or light on the CPU, then either of these CPUs will do the job; if they are CPU hungry, there is a good chance your i5/i7 SP3 will be throttled down to i3 levels anyway. Thus the value proposition for current SP3 i5/i7 Haswell is extremely poor.
I do think Surface Pro 3 is a great concept and I really like the ergonomics of it, but I disagree with Microsoft going ahead and putting in powerful CPUs that obviously overwhelm the SP3's cooling solution in short order - then charging people much more for these flawed designs. Either the cooling solution should be beefed up for the i5/i7 or different CPUs should have been selected altogether. I respect the opinions of others on the topic but I do not think the above 3 points should be dismissed, either.