In general, the rationale would be to avoid backporting risky changes into a long term support OS, since they could affect stability. In openssl's case I'm not

In general, the rationale would be to avoid backporting risky changes into a long term support OS, since they could affect stability. In openssl's case I'm not sure to what degree they've done any kind of stability-affecting changes in the lettered-subversions, so I don't know how well this applies here.