I tend to agree with TML, well I guess having an ex filling station on a main road gives me no choice!
Last year I was thinking of doing putting a car wash on the front of my forecourt and shifting the cars around to the back compound, thus making them more or less out of sight from the main road. I then worked out how many sales that I did from walk- ons and whilst it wasn't was it was, it was still a decent amount (especially in the summer when the holiday parks are open) so I knocked that idea on the head.
Not far from me there are a couple of main road forecourts on a busy road. Before the internet they where the forecourt of milk and honey and nothing much has changed, when it did hands recently folk were fighting to get the keys. Even now, in 2016, the advertising spend on the pitch continues to be next to nothing.
To answer the original question, no you don't need a road side pitch but it's an extra piece of armoury worth having in my opinion, although in the summer when I'm asked if I have a public toilet/ phone/shelter and having to give directions out every bank holiday it maybe doesn't feel like that!