I don't really think it simplifies things to change every single meeting/appointment/agreed-upon time an hour forward/backward two times a year without changing

I don't really think it simplifies things to change every single meeting/appointment/agreed-upon time an hour forward/backward two times a year without changing the actual clock time. If I have a weekly appointment at 11:30 for the whole year, I don't want to be putting that at 10:30 in some months and 11:30 in others. But if you move the clock an hour forward or backward, it can just stay at 11:30 on every day (though the effective time will of course be different).