I mean, if you think about it from a purely functional perspective, for a touch typist, why would it matter if the lettering on some of the keys wears off?
Idk about you, but I can't feel doubleshot/dyesub lettering under my fingertips, which certainly isn't the case with engraved, painted, laser-etched and sometimes printed legends.
I find some kind of easily visible lettering quite useful, when I'm putting a set on a keyboard—to distinguish different profiles/rows. An obscure use case, but an use case nevertheless.
If it's assumed keycaps with legends (as opposed to blanks) improve accessibility for some users, higher quality printing methods make the final product less complex than backlighting.
I seriously doubt that those extremely minor differences in feel can explain the popularity (among enthusiasts) of more durable printing methods.
If you want to get into obscure use cases, then people who use backlighting to see their keys in the dark will count. If rare cases of accessibility issues are a concern, then you also have to take into account users with bad eyesight, whose ability to see the keys will benefit from backlighting. If anything, that seems likely to be more common than people who will lose the ability to use the keyboard after their letters start to fade. And of course, even lettering that rubs off within days will do the job if you're just using it to get the keys in the right place.
Anyway, the case of different printing methods is just one of the many ways in which people focus on the appearance of their keyboard. There are also keysets that sell on the basis of having different colors, and novelty keycaps that sell for vast amounts of money despite having a negative effect on the typing feel of the key in question. If you're not going to accept that it's okay for appearance to sometimes trump functionality in people's preferences, surely the latter would be a far more fitting target...
I don't think night time use of your keyboard is an obscure use case at all. Buying into high end keyboards that you carry from location to location and use to play games and do business seem to include late night surfing, gaming, home entertainment, and programming, text entry.
Backlit is a GIMMICK within the home use market
If you can't touch type.. you probably don't use a keyboard enough to even justify buying mechanical in the first place..
Looking at your keyboard, and making it pretty does absolutely NOTHING...
For example, lets say you dress up a car... that might get you laid...
Dress up a keyboard is the antithesis of laid-itude...
If WHATEVER you do does not contribute to the propagation odds of either you or others, then it needs not be done..