Cute

Dawww.

Is there any particular reason why this manga never got an animated series?

Nanau3 said in comment #2592500:

Is there any particular reason why this manga never got an animated series?

Because the author says the format of Yotsuba to ! wasn't fit for animation. Some times it can be 4-koma, some times it can be a short story, some times it can be several chapters long.

There's a spinoff show, though.