Cell phone is for voice calls only

I keep receiving those Norton emails that I am not receiving full benefit because I only use Norton on my Mac desktop.  I have a cell phone that I only use for voice telephone calls.  Therefore my cell phone doesn't have any data on it.  I never have accepted the idea of a smartphone.  My computing is only done on my Mac desktop.  With my cell phone, whenever I deviate from voice cells, I get lost immediately.  Because I get lost immediately, I am afraid to even try installing any security on it -- especially when there is nothing to secure on my cell phone.  If there is nothing to secure, why have cell phone security?