If you ride slow enough, or don't wear too warm clothes, you won't sweat. Here in Copenhagen 40% or so commute on bikes, including all classes of society from homeless and gypsies to lawyers and managers. 99% of them do it in their work clothes.
Kick bikes are incredibly unstable compared to bikes at their typical low operating speeds, and positively unusable at anything approaching biking speed.
Unfortunately, if you live somewhere where it gets legitimately hot outside or your commute involves a substantial hill, sweating is non-optional. I work in San Francisco so the weather is good for biking, but my apartment is at the top of a big hill. I do bike to work, but on the way home I often work up a sweat and have to change. However, I did recently order an e-bike which I'm very excited about to avoid that issue!
I can't tell if I am missing the sarcasm in this thread, but 25°C would be considered a cool day in the summer where I live. Today is cool and overcast, and the high is still 28°. Last week it was even hotter.
And that is not even considering humidity. There are some days you can just open your front door and you are immediately sweating.
Kick bikes are incredibly unstable compared to bikes at their typical low operating speeds, and positively unusable at anything approaching biking speed.