Surely though as a union leader you want to get what is best for your members, to do this you have to make maximum capital (disruption), this gets the most notice and hopefully for them forces the employers hand - it is a tried and tested method that has been used for decades, if not longer.
The law has been changed, frequently, to do precisely what you say - despite what many seem to think, unlike the 70s when unions went on strike if they got the wrong biscuits the modern union does only use striking as a last resort....
Modern society dictates that the average union worker needs...