It is an idea that's for sure. I think we can all think of lots of reasons why having burning phones on an aircraft is something worth preventing though.
True. OTOH - if the incident rate is ~8/year, out of ~4e7 commercial airline flights per year, and designing seats capable of 0/year is proving difficult - maybe mere improvement would be a reasonable strategy? Available resources are kinda finite, and burning phones on aircraft are obviously not on the "World's Top 100 Human Safety Threats" list.