It's not a huge change, if you look at the origins.
OD&D, 1970s. Kobold are "weaker cousins" to goblins, mystical little buggers that live in forests and attack you.
AD&D, early 1980s. Kobolds are "dog-like" relations to goblins, now with divine hatred for gnomes.
AD&D 2E, late 1980s. Kobolds finally are their own race, scaly little jerks that make up for their size with traps.
Until AD&D 2E, they followed the Germanic "fae little imps" motif that goblins followed. Except, D&D designers and writers wanted to do their own thing. As you note, 3E is where "kobolds -heart- dragons took off. I'm an AD&D 2E child, but my history lessons say the 5E designers aren't wrong if they go back to the original design of kobolds as fey.