The primary reasons why I love Warioware is for the fast paced reflex oriented gameplay and the insane amount of replayablity and extra content and just the overall weirdness of these games. which makes the Warioware games very unqiue amoung Nintendo's usual IPs. like let's be serious, how many times will you see stuff like this in a video game?
This is the kind of stuff that you can only find in Warioware.
And it really gives the series this very bizzare but quirky charm that makes these games and by extent the series itself so unique and fun.
And the characters are designs are an extension to the series' weirdness.
Seriously there is no doubt about it, these characters have to be some of Nintendo's most unique and creative characters ever.
They're funny, they're weird and they're very quirky, and while not all of them are exactly A+ winners, they're all unique and fun in their own way.
which represents the series perfectly.
In short: The reason why I like Warioware is because they so unique among Nintendo's IPs for their quirkiness and gameplay, from the mirocgames to the minigames to the toys to the characters and the world they live in.
Seriously, there's really not much like Warioware and I doubt there'll ever be.