Obtaining another citizenship really only makes sense if it opens up opportunities that are only available to citizens of that country. For example, visa-free travel to more countries, virtually unlimited rights to own property in that country, and quality of the national healthcare system.
As Lordy said, Mexican permanent residency is relatively easy to obtain and would grant you the ability to live and work in Mexico without needing to dig up your family history.
However, as long as you are still a US citizen, you would still have to report your worldwide income to the IRS and pay taxes on it, even if you obtained Mexican permanent residency or citizenship.