The new Alienware 51 laptop:
So what do you want to compare that with in terms of portability?
(a) A MacBook Pro on its own, or
(b) a MacBook Pro, tb3 dock, external hard drive/SSD, eGPU and maybe a second display... or
(c) an iMac in a flight case?
...because you're not seriously going to be looking at that type of system if (a) fits your needs.
This isn't about snatching thin'n'crispy MBP ultrabooks from the hands of people who love them, its about Apple not having
any deep pan 'desktop replacements' on the menu.
But I have a feeling they do and they balance that with what their vision of the next few years of consumer computing will be.
I think, for the Mac to have a long-term future, Apple need to spin of the Mac as a mainly autonomous division that can start behaving like a top-5 personal computer maker rather than as the iPhone's disappointing elder sibling. Millions of people still depend on personal computers to do their jobs and hobbies because there are things that smartphones and pure-touch tablets (which are now pretty much dead except for the iPad) are useless at. There will be money to be made for years to come, but not the meteoric, Moore's-law-driven growth of the past.
(Its like walking into a white-goods store and finding that they
only sell fat-free fryers and coffee pod machines because there's no windfall growth potential in refrigerators, ovens and microwaves).
At the moment, the Mac designers are just looking for sensation (thinner! lighter!) to justify high prices, cash in on BTO upgrades and offer a range that only includes the top-grossing entry in each class. The entire MacBook range, for instance, now consists of variations on the same theme with progressively larger CPUs, GPUs and screens on (basically) scaled versions of the same chassis. Prefer a keyboard with more travel? Tough. Disagree that USB-3 and HDMI ports are "legacy"? Tough. Want a couple of TB of don't-care-about-speed storage to carry around a media library/archive without needing an external drive? Sell a kidney. Doing something like web development, DTP or big spreadsheets that doesn't bother the CPU/GPU much but needs a 15" screen? Sell the other kidney to get an i7 and dGPU that you don't need.
Apple
are one of the 5 largest personal computer makers - and the only legitimate choice if you want to run MacOS - they ought to be able to sustain a bit more diversity in their product line (Jobs' old 'product matrix' was less sparse, and that was in the context of Apple's near bankruptcy and a more total Wintel monopoly than today).