He's off. Your Droid only needs the required data plan, which covers your texting, etc.
Your other phones likely have texting included in their data plans, or as a separate add on, check that for your other phones, and go to a vz owned store if possible.
I agree and disagree with this post. I agree that your Droid only needs the required $29.99 data plan, however, what is not true is text messaging is NOT included. The only exceptions would be if you're using GTalk or GVoice or another 3rd party service. The stock text message plan is either $0.20 per text sent or received or $0.25 for a picture sent/received.
I wonder if you have a very old grandfathered plan and he maybe said you need to upgrade the plan to a Nationwide Family Share plan.
Were you at a corporate store or a premium retailer? I suggest the corporate store, or call 800-922-0204 or *611 from your VZW phone and talk to customer care.