The ending was too abrupt and felt like a cop out
After I watched it I looked up the HG Wells novel on Wikipedia and the plot summary says the cause of death for the Martians was the same (they have no tolerance for Earth's germs) but the way the film handled just felt way too abrupt - the humans are all cowering in a church as the Martians are marauding down the streets, the end is nigh... then they crash and die! Then the narrator explains it was the bacteria that got them. The End.
Instead of going through the usual stages when living things contract an illness, getting sick and weak and gradually dying, the Martians seemed to skip all this, going from being alive and able to pilot their craft and blow things up to keeling over and dying.
It was almost like that bit in Monty Python and the Holy Grail: "...then suddenly the animator suffered a fatal heart attack! The cartoon peril was no more."