My understanding is that the "unbearable thinness" is what happens when Computer Modern outlines designed to accommodate ink swell (associated with older printing methods) are used on modern display and raster printing surfaces without adjustment. If you check the typography in TAoCP, which Knuth fine tuned, it doesn't seem so unnaturally thin.

Do you happen to know how he fine tuned it? I too would like a bit more weight on the font when printed.

You are supposed to fine tune the constants yourself for your specific printer when installing TeX and METAFONT on your system.

The pre-defined modes can be found here: ftp://ftp.tug.org/tex/modes.mf

The art of optimizing a typeface for print is pretty elaborate, and if you're genuinely interested in learning how to do this, https://typedrawers.com is a good place to start. It's where all the font engineers, as well as foundry owners, hang out.

Set your printer to 300 dpi.

No, seriously, when UTCS replaced the 300dpi laser printers with 600dpi models, Allan Emerson was very upset because his papers suddenly looked different. :-)

FYI on modern LaTeX engines like LuaLaTeX (and also XeLaTeX) Latin Modern actually is the default.

But Latin Modern and the default Type 1 version of Computer Modern have exactly the same thickness, so if Computer Modern looks thinner for you then it must be some weird screen effect. (The hinting is a bit different, but I wouldn't have expected that to have a significant effect on current systems where hinting is often ignored anyway.)

AFAIK, Wikipedia's info on the Latin Modern regressions from Blue Sky is accurate. Neither version is the original CM font or has had as much fine-tuning put into it, but (EDIT) the Blue Sky version was at least worked on by paid professionals.

https://en.wikipedia.org/wiki/Computer_Modern#Latin_Modern

Yes, it looks thicker in print [1].

[1] https://www.flickr.com/photos/lonelyfox/4329034436

Is that Computer Modern? Wow. Looks very different from seeing it in a PDF.

You just need to update your reader. Any decent PDF or even DVI software has the ability to display CM in a readable way.

That is not true in any way.

First, the main way PDF readers make strokes thicker is via hinting, so it depends on how Computer Modern was embedded into the PDF for starters.

Second, hinting distorts letterforms so many top-quality renderers (like on macOS) don't use it, preferring more accurate letterforms instead. And Preview on macOS is certainly "decent".

Third, "updating" isn't going to do a thing. Whether fonts are rendered as hinted or not is a design decision taken when the PDF rendered was built from the ground up. No "update" is going to change that.