Why would a font creator do that?
You also have to look at the fonts like a whole collection of works of art. Fonts are one of the best examples of why you can't always take an image and easily zoom in OR out and still end up with something looking how you want it to.
Each letter of each size/style is hand drawn, and many fonts will do far beyond the normal 120 or so ascii characters, offering extended characters and symbols.
And because fonts zoom very badly, they typically have to draw them again for each font size. If the font shows in the popup with available sizes of 8, 10, 12, 14, 16, 20, 26, 30, and 40 pt, that entire font was hand drawn
nine times. The personality of a font really becomes apparent at the larger sizes. Then start more multiplying again when you apply styles. If each of those has merely a bold and italic, now you're talking
twenty-seven redraws of over 100 characters. Yikes. I know if
I did that much work, I'd want to get paid something for it!
The bugger is you can't always just substitute one font for another and maintain layout, especially at larger sizes. Not many fonts are mono spaced, and as a result, characters like "i" are not as wide as "w". If you don't have the correct font loaded and the system has to substitute something close, a "w" at 30pt could easily be off in width by several pixels. Over the length of a line, that will affect line wraps, and really mess up your copy.
So not only do they put a lot of work into their fonts, but they're very well aware of just how screwed up things can be for you if you don't feel like paying them for it. Even the small print houses we have here in town easily have 3-20
thousand fonts purchased. Some from the OS 8 days. (FontFinagler is very useful for converting format from old style to new so they work on the newer OSs)
That being said, many document formats can package in nonstandard fonts, but those fonts don't usually get installed into the system, they're just used for viewing the document. So if you receive a document using a font you like the looks of, you can't just create a new document and select that font, it won't be listed. So you're probably going to have to buy it anyway even if the font was bundled in.
Also worth noting that when you send a document to say, a laser printer, if you send it as text it will have the same font specification in it, and if the printer lacks the font specified, it will substitute it and the same abovementioned chaos sets in. Higher end apps like Pagemaker and Quark send copies to a printer as raw data (like a picture) to avoid this problem so WYSIWYG, but apps like Word and AppleWorks won't do that. I've ran into many cases of the printout not looking like the preview window. (both in character separations and line wraps)