If the mood of the past couple of years of the Mac needed to be summed up in two words, I'd nominate "professional angst." Lack of updates to the late 2013 Mac Pro and the MacBook Pro caused consternation; the eventual new MacBook Pro release walked into a tough room and failed to impress. Pro users were up in arms, to the point where (after two vain attempts to reassure them through oblique Tim Cook statements) Apple took the unprecedented step of inviting five journalists to Cupertino to acknowledge its mistakes and promise better things in the future for pros.

But what is a pro Mac, really?

It's a Mac that's used by professionals, sure — though, as I learned long ago, most professionals use their Macs for more than just work. The next question, then: What is a pro? I'd argue that it's anyone who uses their Mac as the primary tool by which they make their living. This is a broad category that covers a lot of ground, I'll admit. A bookkeeper who spends most of her time in Excel is, by my definition, a professional user.

Different professionals have different needs, of course. For years I said that I could continue to do my job using the PowerBook 160 I bought in grad school, so long as it was still equipped with a copy of Microsoft Word 5.1 or WriteNow 4. After all, the alphabet hasn't changed, and writing is still the job of pushing that cursor from left to right across the screen.

But I can't really claim that anymore because my job requires access to the Web, and my old computer couldn't do that job very well at all. (Novelist George R.R. Martin still writes his books in WordStar on a PC running DOS; but he has a second computer next to the first for him to use to run modern software and access the internet. That PC is barely even a computer — it's a fancy typewriter.)

What makes a "creative" pro?

Most of the professions we associate with the Mac are creative ones, largely because those professions provided most of the Mac's userbase in the 80s and 90s. Designers, artists, musicians, and video editors are commonly Mac users. And don't forget scientists and programmers — you can't write iOS software if you aren't using a Mac, and Xcode is a legendary resource hog.

So many of these professions are incredibly specific: In the industry they're generally referred to with the buzzword "verticals," so named because they are narrow (i.e., there are very few users in any given category) but require great depth (in terms of the specific demands they put on their hardware and software).

Over the years, "pro" became synonymous with this more expensive, high end of the market — because while every profession is a bit different, most creative professionals wanted to push their computers to the limit and were willing to pay to get the very best tools to do their jobs.

Traditionally, that need for the very best manifested with machines that were the fastest you could buy — the niche the Mac Pro is supposed to fill today. But the rise of powerful laptops led to a lot of people weighing mobility over power and moving to the MacBook Pro. For some professions, portability is king; it's why the original MacBook Air could sell for $1799.

The truth is, every professional user is the most vertical of niches: a target market of one, with specific needs and desires that need to be fulfilled. Very few of us are lucky enough to have the perfect product emerge from Apple's factories, so we have to pick and choose and find the closest approximation that we can afford.

That's the advantage of making professional products not just powerful, but flexible in terms of specs and features. The more flexible the product line, the more fuzzy space there is for professional users to fit inside.

Learning from the Mac Pro

Where Apple clearly went wrong in the Mac Pro (and arguably with the MacBook Pro) is in creating products that weren't conceived with flexibility in mind. The 2013 Mac Pro was an opinionated product in classic Apple fashion, but the resulting design had so little flexibility and upgradeability that it became a rare misfire. I love how Apple approaches product design with an opinionated streak — "this is our vision of the future, take it or leave it" — and in consumer markets, those opinions frequently pay off.

But in professional markets, Apple's approach to product design backfired. Starved for new Macs and more power, Apple's product releases (and lack of same) had cornered its professional users. You never know how a cornered animal will react — but it's generally not good. Apple's professional users had their backs to the wall, and the reactions were understandably ugly.

Apple's conversation about professional Macs with members of the press, strange though it was, is a positive sign. Apple's executives also came across as understanding that the products they had been making weren't flexible enough. They didn't provide enough of that fuzzy space for niche markets of thousands or hundreds or dozens of users to fit inside.

Does every professional Mac user need a Mac Pro? Absolutely not. But the Mac Pro is important to the Mac market as a whole, and not just as a symbol. It's important as a release valve. If you can't use a Mac mini or MacBook or iMac and MacBook Pro to get your job done, the Mac Pro should exist — at a cost, of course — as the solution to any problem. Its job is to keep the most demanding users on the platform.

And that's why the Mac Pro is important to all professional Mac users — even if most of us won't end up buying or using it.