In regard to CHIP being supported and 2d not, it could make sense... When companies decide what to support the would have way more potential enhancements than would actually make it into each release, therefore they need to prioritize.
Presumably your older unit has other 2d options but doesn't have CHIRP so supporting this new feature would add something to that unit you don't already have. Also its my understanding that CHIRP would do about the same as 2d but potentially better. So I could see Humminbird thinking that would support CHIRP first and then look at putting the money and time for 2d into other features ahead
Again assuming its not a type o. Just remember every supported feature needs to be planned designed coded and maybe even hardware design and speed and capacity issues, and time to market etc, so there are many reasons beyond what looks easier to do that goes into any feature