Some cultures like those stickers. Japan and Korea for example. So calling them stupid is arguably calling both Korean and Japanese culture stupid.
In Japan the #1 messaging app is Line. The stickers are so popular and so well known there is merchandise all over the place based on the default stickers.
You should give them a try. It’s actually pretty fun IMO. The default ones in FB Messenger are ugly but some of the optional ones are very cute and often help add emotion and levity.
