Several years ago I got a Samsung Solstice when I renewed my plan (no data required at that time). I did not like the phone so after 2 months I put my card back into my Centro and have been using it for 1 1/2 years. I believe that was one of the last phones you could use without a data plan. I see the phone as secondary to the plan I purchase and shouldn't matter which device you use.
We had a situation with Verizon. My father-in-law died and we were using his phones while clearing up the estate. One was stolen and we asked if we could transfer the phone number (this had been his main phone) to the remaining phone and they said only if we signed a 2 year contract. Since Verizon has to physically set up the phone with the number then we could not just use that number with the other phone. This feature is one of the reasons I like AT&T. I lost my phone and was able to purchase one on eBay along with a SIM card, activated the SIM and phone and I was back in business. I was never questioned about i,t that's why I say it is the plan that counts, not the phone you use. However, that being said, with the current phone offerings I believe you will need to purchase a data plan.
Forcing someone to purchase a data plan just because they like having a smartphone is unAmerican.
I would not feel guilty, after all, it's not like you went out and bought a new phone that required a data plan, you just put an old one back into service.