Good discussion here.
Legacy vs. Discontinued
To me, "legacy" and "discontinued" hold very different meaning. We originally picked "legacy" to communicate that the Photon and Electron are part of an "older generation" of products – our 2nd gen product family, as Rick mentioned above.
"Discontinued" refers more specifically to its availability from Particle. Because the Photon and Electron are legacy products that have not been discontinued, the message we want to communicate is that they are not a part of the newest family of products, but that they are still available for purchase.
With a better understanding of our intent, is there another phrasing that you'd recommend that would better carry that meaning?
In the meantime, we can update the language in the documentation to refer to "1st gen", "2nd gen", "3rd gen" rather than to group 1st and 2nd gen together under "Legacy".