The extra roadwheels (removed with transport tracks) were necessary to carry the weight in rough terrain. I'm sure they would have liked to travel that way too, but no rail system could take the width. As it was, they needed special cars just to move the Tigers, another logistical nightmare.

Without falling into stereotypes and cultural differences, Tigers were built as precision machines in the same manner as locomotive engines. That's a big reason behind only 2500 or so being built. They were amazing weapons, but hard to put into use. On the flip side, 60,000 mass produced Shermans may not be as well constructed, but are easily transferable and repairable with a lot of support, so ultimately more successful.