Good question! Could it be to supply power to more wheels so that the locomotive has more traction and can pull a longer train, since a 2-10-0 is usually used as a freight train? If the tender is properly close coupled then you would not see the shaft anyway so it wouldn't matter then, and you can always slice the legs off the crew!
Do the Roco locomotives have traction tires or not? Perhaps Lilliput and Fleischmann have them on the tenders?

Do the Roco locomotives have traction tires or not? Perhaps Lilliput and Fleischmann have them on the tenders?