Generally I think in the US we lean too much against having commerce in and around parks, failing to recognize that making places accessible to humans requires things which support human activity like food and other kinds of retail.
Because the small square is surrounded by businesses, I don't think it's a park which actually needs more commercialization to be enjoyed by people, though it may need it for its finances, but still I love this response to the suggestion.
She ruled out advertising inside the square, said that 18th Street might be closed for special events in which Friends would share in vendors' revenues. There might be a seasonal 8-by-12-foot concession booth in the square and maybe more special events within the square, she said.
That letter was answered by an anonymous two-page letter calling Rosen's plan a "disaster," adding that it would be "opening the square to hoards of people and businesses," which sounds a touch, mmm, elitist.
"We have a fabulous square that only needs support from its surrounding residents," wrote the anonymous author.