I plant out my tomatoes deeper than they were in the original pots to encourage more root development, which does mean the lowest leaves are touching the soil and are prone to die off and rot, so I remove them to avoid potential problems with botrytis.
Apart from that, I do what Mum suggests, although I sometimes remove leaves jammed up against the greenhouse glass because they tend to trap moisture - another potential health issue to be avoided if possible, although obviously not applicable to toms grown outdoors.