Because it does the whole process for you and you don't have stand over it, you can switch it on and clear off no do something else - I rarely made soup before but I use mine nearly everyday, especially in winter.
Not laziness, Bernie.......makes great soup while you have a manicure.....crochet a blanket square.....plant a shrub...so soup maker owners get far more done than those who use a saucepan.....
Mine's a Morphy Richards.......bliss.....x
I don't watch my pan of soup and it takes less than a minute to blend it with a hand blender - all of which I already have so why spend money on a soup maker?