Of course I enjoy leveling up and choosing skills and exploring dungeons, but plenty of games implement those same mechanics at least as well as DQ. For me, the distinguishing feature of the Dragon Quest franchise (today*) is its charm: The charismatic cast of endearing enemies. The regional accents of the NPCs. The wordplay, the art, the music. Even the venerable hanging leather sack is enough to make me smile.
*I say "today" because earlier translations were not very good, as the article mentions. As I recall, even DQ7 on PS1 was pretty rough. But the English localization of DQ8 in 2005 was a masterpiece, and I think this is the one that set the bar for the future of the franchise (including remakes of earlier entries).