I didnt say good expressive music was metronomic,however good dance music needs to have a steady beat,the metronome is a useful tool,in helping to prevent speeding up,and in a diagnostic capacity ,to work out approximate dancing speeds for tunes,
of course some jigs[like all tunes] feel that they want to go slower and some feel that they want to go faster .,again a metronome can be useful here, like LARK IN THE MORNING [better at 120]Walls of liscaroll better at 115,it is just a tool for training,but if more people used them,I think there would be less breackneck speeding.