She clearly was dumber naïve then, and Tohru and Kobayashi (all the chaos dragons actually) have both made her more wise to the world.

Tohru's point has always been that the humans of their world are prone to evil. They will find ways to seize power. They will claim the power dragons (an external force) give them, either by slaughtering Chaos dragons for fame (with Tohru and Ilulu's case) or by bribing Harmony dragons and using them for protection, with Elma here (and Luoca too, I believe). They were bribing her with human food, and judging by Elma's reaction to Earth's food, not particularly great food either. Elma's intentions were good, but the humans who she thought she was helping were taking advantage of her.

The obvious comparison, is that Earth has the same problem, just not in Japan at the working-people level.

Tohru did open her eyes to what they were doing, because Elma never tried to directly help humans by living among them after that. If I remember season 1 correctly, Fafnir has taught Tohru the same lesson that Tohru taught Elma.

It's just that none can resist the pure heart of Kobayashi.

But the real highlight this episode is Ilulu achieving her dream of playing with children all day and making them happy.