That is a brilliant idea!
In fact I did just that but in different circumstances - my smartphone wasn't working at the time, and I started using an old feature phone. But I found such relief knowing that I don't have to check for anything on my feature phone.
I was tempted to buy the new Nokia 3310 when it came out last year but then dropped the idea. For one, then I cannot use an app like eSteem which makes things convenient for me. I even write posts on my phone when I am outside, using a writing app. I may miss those small conveniences if I use a feature phone.