>>527333148
The more I think about it, the Dreemurrs are kinda like public figures within Hometown that have an image to maintain right? Asgore was part of the force and they're close friends with Mayor Holiday.
So it wouldn't be surprising if they adopted the only human child because it would've improved their image. They're "uplifting" someone in need and helping them integrate into society.
I do think Toriel and Asgore were trying to be good parents too, but you can't tell me public image wasn't PART of their motivation.