Why? St. Mary's public transport links are excellent.
At least 3 train stations within walking distance of the ground, one of them a major hub with links all over the country.
A decent public bus network all over the city, some of which has even been free with a match ticket.
Hythe and IoW ferry to walking distance from the ground.
There's even an airport, which is then accessible to the ground via one bus line or a train.
For those driving there is also a decent out of town park and ride.
Edit: and a National Express and Greyhound coach station within walking distance too.