I always supply logistic elements for my 6mm forces. All my artillery batteries have tows. I have tons of wagons and lorries for supplies and transport too. When I still had them, my WW2 Germans had horse-drawn limbers for the artillery and wagons, as well as the usual range of lorries and tractors. My tabletop would not look right without these elements, to my mind.
It’s also worth noting that sometimes the logistic elements are integral to the running of the battle, as well as looking pretty. I play WW2 rules where there is a chance that ordnance can run out of ammo, and you need somewhere to resupply them from. The supply units provide that option. There’s loads of other ways to use them too, such as making them the focus of a scenario, using them as markers for various statuses, or just for prettifying the table. Although I generally loathe painting, I love sorting out these ‘non-essential’ elements for my games.