I mean, leaving aside the very literal way this Dream ended up coming true… It's also obviously very important for Cake's character on a deeper, thematic level.
Cake is performing a facsimile of a Normal Adult Human Relationship. Quite literally performing since she's in a little cardboard sitcom-set, surrounded by cameras and a studio audience. It plays into Cake's anxieties that her personhood is just some sort of 'facade' for her animal nature (a fear that Huntress Wizard has really fed into with that last episode).
And also in general just how much her sense of self-esteem and self-image has been dependent on how others view her… cause, again, she is on a Sitcom Set. Being watched by the Live Studio Audience. The same kind of audience that treated her like a Freakshow and then booed her for acting 'like a cat' just a few days ago.
Specifically performing, like, a Heartwarming Sitcom Baby Birth Scene… and, well, when this dream came true, it did so by making the Kitties analogous to the toys Cake sleeps with. I'm pretty sure I said it before that at least some of Cake's attempt at 'normalcy' seems to be analogous to, like, trying to fit into an arbitrary standard of being 'Adult' and 'Mature' so people will respect you.
And here she is reenacting one of the most strong-enforced concepts of what it means to have a Normal and Mature Relationship in society, that the endpoint has to be 'starting a family'.
Then she gets a bucket filled with five furry reminders that she is a Cat With Weird Powers. And her first instinct is to recoil from them…
She regrets it immediately, but still she ends up accidently hurting her Pups Kitties and herself.
Obviously the Kitties don't exist (yet?) in Fionnaworld, but the idea that Cake's insecurities about not being 'normal' could hurt others (especially M-Cron) feels pretty likely to me.
Also it confirms that Jake's Weird Thing with Mr. Cupcake transcends timelines and universes, and that's also important.
