The original reason we wanted to change instance a year ago was because the default Mastodon UI made me vomit with how ugly it was, and at the time girldick dot gay had a really nice custom theme that made us really happy in a difficult to describe way. It was really easy to see and made us feel cosy and safe and like a sweet princess, and so we (but especially the littles in our system) wanted to make an account there.
A couple months ago a mastodon update broke the theme , but we've continued using it since we largely no longer use websites anymore for fedi, and just use moshidon, and it's just easier to stay where we already are.