One of the things that came up at our annual meeting was the need to have information on how we are hurt by not having a ballot line.
I can think of a few:
1) Political parties can form PACs with no registration fee, but others have to pay a substantial annual registration fee (around $100 or more if I remember correctly).
2) A few people have come up to me and said something like "I wanted to vote for the Green candidate but I couldn't remember his/her name."
3) Local press tend to give automatic coverage to political parties but generally give little/none to independent candidates (even with substantial prodding on the part of the campaigns).
Other reasons why we would want a ballot line?