Maybe I'm lazy[1], maybe I'm an Elitist Bourgeois Pig-dog ANSI-like Lover, but I've never really played around with tilesets to any significant amount.
Which means that when someone posts an alternate-tilesetted printscreen, I'm often not a little lost for the fine detail. Which is not to say that I wouldn't immediately be able to tell the difference between a goat and a particular type of goblin, or a gosling and another type (something that the default would, and does, cause trouble with), but I reckon that unless it's a particularly well-drawn tileset across all the other visible features, that I might well have problems with something else depicted even if (perchance) I can quite clearly see that it's a small anseriniform, something definitely caprinous or a vicious-looking unnatural creature holding an identifiable weapon.
When playing the game, in either Adventure or Fortress mode, I suppose I could suffer a tileset, because I could pause it and check it the full details of an unknown image. Because I do that with the default graphics, anyway, and no tileset could possibly reveal that on this particular garbage dump there's 192 lumps of raw sandstone, 19 assorted bits of vermin remains, some wilted plants, a rather badly damaged sock and a marble door that I've unforbidden but hasn't yet been returned to service after an ignoble and forced removal from its prior locale...
Basically, as an abstraction, ASCII/ANSI-like/Codepage-whatever 'graphics' do it for me, as well, and I've not yet been tempted by the (admittedly, almost always nice-looking) alternatives that have doubtless been slaved over by people much more talented (or patient) than I in the graphical arts...
TL;DR; - Graphics packs are just not (yet) for me. But I can see their value.
[1] Although I will change to value-depths for liquids, set up all seasonal/on-embark auto-saves and have been known to modify the inter-cavern gaps, but am generally lazy about doing anything else to the defaults.