Cancun's (poor) reputation as a foodie mecca is deserved - especially in the hotel zone. Since severely damaged by a hurricane some years back (Wilma in 2005?), the hotel strip has rebuilt. Most everything there food-wise is designed to please drunken college students on break or older folks who are not exactly adventuresome.
Get a cab, go into town, and have dinner at La Habichuela. Yes, it's touristy as well, but the kitsch has a certain charm. Plus, you'll pass through town, thereby seeing something of Mexico.