A lot of what you say is valid. Macs are reasonably stable, have good build quality and are superior to generic PCs in some circumstances.
A lot is just BS. Macs are not the best choice for everyone all the time. The best way to describe their "target market" is "fanbois and arty types". Sorry, but it's the truth. I also doubt you'll find any reliable evidence saying Macs give less trouble than branded office PCs. I think the opposite is true. It's possible these days to build a Windows PC that's more stable than any Mac could be.
It is possible to do anything. Yes the PC I type on is a Panasonic Let's Note and yes I can drop it 78 cm, sit on it, spill water on it or bury it in snow - but that also comes with a price premium. You won't find a Dell, HP, Sony or Acer with those sort of specs either. The build quality is incredible BUT it has issues - it can't be booted by most Linux or BartPE bootdisks for example. It's also quite a slow CPU (although low power draw) and has no ExpressCard slot because Panasonic Osaka thinks the average salaryman doesn't need those features.
You are however making a sociological statement which makes no sense. Can you prove to me - and I assume you are knowledgeable in sociology or psychology why 'arty types' would find a well built, fully laden notebook with a great OS to be something for them as opposed to Joe Average. Sure Joe Average usually buys Celeron driven generic machines - but then the people who buy high end AlienWare, Dell and SONY Vaio machines - those are priced comparatively - are those also machines for 'artsy types' or some other stereotyped sub-grouping of society?
In the corporate and consumer mass market, Macs are not what people want or need. They want certain boxes ticked, and at the moment the Lenovo mentioned ticks all of them. The Macbook doesn't even come close. (The Lenovo's build quality isn't the same as it used to be, it it's still as good, or better, than anything else in it's class. The Toughbook isn't in it's class.) I can think of very few markets that would choose the Macbook over a branded PC notebook.
The FULL RUGGEDISED Toughbook isn't but business Toughbooks - aka
Let's Note and machines made by NEC (LaVie, VersaPro, Versa) beat Lenovos by far in terms of build quality and Osaka and Tokyo respectively make sure to put in only what businessmen need and nothing else. These machines are in Dell and Lenovo's class in terms of target audience and price (you will always get a lower RAM and slower CPU machine for the same price from these makers though but for business use it's not too bad) - these are not the fully ruggerdised laptops from Panasonic US marines or paramedics use in the field.
As for Office for Windows and it's UI being inferior. The OP's test case disagrees, and so do I. Even if it's just the stress and expense of the changeover that is discouraging this worker, that is enough reason not to chance. Why got through all that stress for best case: a SMALL increase in productivity, MAYBE.
AFAIK the RIBBON in MS Office for Windows is a bigger issue to grapple with than Office for Mac. Entourage apparently is also more stable.
I think you're just referring to Macbook Pros being for 'artsy' types because they are brush aluminium and what-not. But they are sturdy machines. They are also fully laded - they have TWO GPUs, a high end CPU, lots of RAM and a high end screen which you can get in matte too. Now if you're only using a latop to run Office apps - such a monster is too much - but so is a top end Lenovo and every Sony Vaio out there - but if you have R13K to spend on a good quality machine with lots of features and good build - the Mac Book (not Pro) is a good contender. It can run Windows and OSX and OSX is more stable.