As a designer, absolutely. The exact weight of a font can make a ton of difference in a finished product, and it's frequent to be frustrated that the font isn't available in the weight that would look right for the needs -- you need something in between semibold and bold, or something in between regular and condensed, or something oblique but not that oblique.
It's the difference between a design being good, and a design being beautifully "just right" with everything perfectly in proportion.
So for that, variable fonts are a godsend.
That being said, I've never seen a slider between proportional and monospace before. That's just weird. :)
If I want to show something that looks like code - like an HTML tag or something - at a heading size on a page or a poster, a proper monospaced coding font is going to look bad. Playing with the MONO slider on https://www.recursive.design/ for a string like '<blink />' does a good job of producing something that looks like code but isn't swamped with too much whitespace...
https://www.myfonts.com/fonts/linotype/neue-helvetica/
Also, Helvetica is popular in large part because of the very precise personality it has with is quite amenable to the image corporations often like to portray. It become widely available on computers, starting with Macs, because it was already such a useful font. Major corporations aren't choosing Helvetica simply because it's a default font on computers. And, of course, it's not like a majority of companies use Helvetica for their branding or anything -- it's a popular font, but where popular means maybe 3% or 5%, not 50%.
Helvetica was put on Macs because it was so popular as a useful font, rather than it becoming popular because it was on Macs.
Take two was Adobe's Multiple Master extension to Type 1. Technically this is still used by Adobe Acrobat to handle fallbacks for missing fonts, but as an end-user technology it was a failure, largely because of difficulties in being able to use the interpolated fonts—few applications allowed direct selection of interpolated designs and users had to generate them in ATM instead.
So now we have the third attempt, with better application support, which has some hope of success. For text type users, the appeal is the ability to finally regain optical scaling for type designs. Traditionally, as a type design was created at a smaller size, it would become relatively darker with less contrast. Perhaps the most dramatic example of this in everyday use is to compare the spindly appearance of "fake" small caps with the more robust appearance of properly designed small caps. So this is one case where, yes, we really do want this ability.
The HN audience loves to discuss the bloat in web design -- If you can reduce 500kb of font-<heavy, bold, italic, light> files into a single file that interpolates between font vectors dynamically, that goes a long way to avoiding excessive resources. And you also get the benefit of being able to tweak the parameters of each font style without changing out static files.
For example, with Recursive the entire static font family come in at 12.8mb, while the dynamic font family in a single file is 1.45mb. Obviously you wouldn't load up every variant and Recursive is a very large font, but I could certainly imagine replacing ~8-10 font files with a single variable font.
Generally with web design, you want to stick to a small number of font weights anyway so if the file size isn't smaller, what's the core motivation?
The key thing also is the number of web requests. This is not a trivial detail. One variable font can be less web requests.
Is the number of web requests a factor if you're using HTTP/2 though?
And yet no way to decrease the x-height. I'm sick of fonts where the lowercase is tall and the uppercase/ascenders are short.
It was a bit frustrating viewing this site on Firefox and not having any indication of why the settings weren't changing anything.
Of course, maybe that's because there hasn't been enough demand for it, and now that there is a font that's widely available which can use this, Firefox might finish enabling it (looks like there is a flag for it, but it's not enabled by default).
https://caniuse.com/#search=font-variation-settings
And I am running an ancient version of macOS, 10.12, which explains my issue, as it's only supported on macOS 10.13+ in Firefox.
I have a new (non-macOS) laptop in transit, but my current daily driver is an old Mac.
Sorry for the alarm!
Seems to work fine for me on Safari
So, the Recursive minisite has a configuration tool (under the “Get Recursive” button) that makes it easy to get Google Fonts embed code for all axes.
There are four dimensions and a few other flags that the font can be adjusted by in CSS: natural-width to fixed-width, Linear to "Casual", Font weight, Font slant, and cursive variants.
By tweaking any of the variable font parameters it you can get anything in the range of a "serious" monospace font to a more casual font useful for UI mockups. I don't spend a huge amount of time in the font design world but this is one of the first variable fonts I've seen that feels less like a gimmicky demo and more like a seriously versatile tool, really great work!