1) Republic Wireless already offers a wifi only smartphone plan for only $5 and offers on the fly plan changes to allow using the phone over traditional cell phone networks: $10/month for all the wifi you can eat and includes cell voice anywhere on the sprint network. For $25 a month you unlimited phone, text, and data over wifi and sprint's 3G network. You can make plan changes up to twice a month.
2) If Optimum was smart, they would have made this free to their customers as a value added to their accounts to keep customers loyal. Might have been smart to offer this for free to non customers too to try to get new customers for their cable service.
As it stands now, the Republic Wireless plan is less expensive and offers better choices to add services later, They also offer Moto X, as well as the Moto G so there is a choice of phones too.