iPad Mini 2 has 1 GB of RAM where the original had half as much. Typically Apple has only deprecated old iOS device models from new OS support due to hardware requirements.
If they allow an iOS version to be compatible with an under powered device that can barely run it they'll get criticized for slowing down older machines or even accused of deliberately crippling them down to force upgrades.
If they don't allow new iOS versions to run on older machines with lower specs, they get accused of deliberately deprecating older models to force upgrades.
Yeah. They wound up selling the iPad2/mini1 guts far longer than I would have thought smart. My iPad2 was feeling long in the tooth well before it stopped being sold new. (And I'm not the most demanding iOS user).
