I do respect your choice for CC BY-SA. Licenses are a personal choice and iNaturalist is great for supporting this personal choice.
Having said that, I disagree with your encouragement for using CC BY-SA. Since CC-BY-SA also hinders scientific re-use, which you acknowledge by mentioning that CC-BY-SA observations are not included in GBIF.
Creative commons makes total sense in the arts, where the composition of an art form is key. However, this is not the case in iNaturalist where one deposit recordings of observations with the mere objective of it getting annotated by the iNaturalist community at large. Then the question becomes how you license those annotations. If I, a proponent of CC0, would annotate one of your observations, you relicense my annotation as CC-BY-SA, by which you don’t respect my choice for CC0 as a leading license, by annotating your CC-BY-SA I have to share that annotation with your license. That is why ND, never makes sense. The ND part forbids derrivatives, which an observation with annotations is.
But let us stick with your default choice of CC-BY-SA, I have indicated at iNaturalist that all my contributions should be CC0, this applies also to my hypothetical identifications of your CC-BY-SA licenses. So basically, by doing so I am breaching your requirement to apply CC-BY-SA on your observations.
Then again there is this claim that one cannot apply copyright on facts. I have been trying to get this confirmed by different legal scholar, where the default answer is “it depends”, where they never continue that answer on what it depends. The closest answer I got is that these things are only solved through litigation.
Long story short, available license choices is a big mess. That is exactly why I am releasing all my contributions on iNaturalist under the CC0 license,. Maybe some will earn some money on my work, but the alternative is to litigate any breach of that license in court. For me that is not worth the effort.
I am into the game to have fun, not to empower a legal game.
Again, I don’t expect you to change to CC0, I am just objecting to your suggestion to change to a general license of CC-BY-SA. The issue with GBIF seems to be solved soon, so we can all just use our prefered license, which is a policy I hope more citizen science platforms would adopt.