I think if you are making over 100 grand a year with no kids or debt then its not a huge deal if you want some flashy toys.
I'd rather put the money into a higher spec system, as I don't need a display of this calibre. Moot as I only work internationally, If I was working predominantly at home a different situation. Mac Pro and the display are expensive, equally for those that can utilise and make a living with such hardware it's not such a deep investment given the longevity of the system.
In comparison minimum spec MBP I'd consider is over $4K and I'd be looking at swapping it out after 24 months. A Mac Pro I would consider being good for at least 4-6 years, more depending on the ability to upgrade. Similar to the iMac Pro the Mac Pro is priced reasonably fairly for what you get in comparison to the likes of a HP Z Workstation, although the HP's chassis is more flexible at the cost of being a more utilitarian box.
Problem is many hoped Apple would offer a Mac Pro for the consumer & hobbyist at far lower price point, however that's not Apple's target audience. The organisations and vast majority of individuals who purchase the Mac Pro will do for one sole reason with it being an asset to their business and a function of profitability.
Personally if I was bound to an OS X workflow and not in a mobile position I would buy a reasonably spec'd Mac Pro as for me it would pay for itself fairly rapidly and certainly offer far more longevity than any Mac notebook ever will...
Q-6