The bill would reimburse kidney donors for non-medical costs associated with surgery such as wage reimbursement — the median costs are as high as $4,000. There is good reason to believe that removing this disincentive would cause a non-trivial increase in kidney donations (see this study, esp. Table 2). If it increases living donations in New York by 20% (which is what a similar policy accomplished in New Zealand), that would mean over 100 additional donations per year. See here for a detailed breakdown of the benefits of receiving a kidney for the recipient (though some of the figures are a bit out of date, living donor transplants probably last longer now).
In addition to being directly good for the world, this policy change would be a great win for the effective altruism community — Waitlist Zero, which is supported by Open Philanthropy, has led the advocacy for this bill, and others in the EA community helped it pass the NY Senate.