NIANTIC, reward suggestion
During some time let all Legacy/Community Day moves being accessible through TMs.
Answers
Making the regionals rare hatches is definitely a not-so-subtle ploy to force incubator sales. I myself am 36 eggs deep without a Kangaskhan yet and am closing in on a point of needing more incubators to try to hatch one. That said there's a key difference between selling a "speed-up" to a trophy and selling objectively more powerful versions of Pokemon. It's a similar comparison as games where you can buy skins for your guns and keep them functionally the same versus simply buying more powerful guns. Nobody is using any of the regionals competitively, there's less sin to selling incubators to collect more of them.
Adding regionals to the 7km eggs isn’t even remotely as bad as selling special TMs. Buying an item to get the most powerful version of a Pokémon (SC Gengar, SD Tyranitar, community day starters, etc) is pure pay to win. Regional Pokémon are not strong (except maybe Heracross and even that’s a stretch), and you’re not forced to buy incubators to get them. You can get them in the wild by traveling, trade other players, use the free incubator, or use daily coins from gyms to buy incubators. It’s a slight cash grab, sure, but not nearly as bad as straight up buying the strongest Pokémon. If I could just TM 3 more SD Tyranitar and 6 SD Gengar that would be ridiculous, not to mention it takes away the whole novelty of community day moves like DP Ampharos.
How about making a special move TM available through a research quest. I think it's possible that's how Origin Pulse, Precipice Blades, and some other killer special moves for powerhouse Legendaries will play out. That limits it to one per person, so the hard core players won't take on fire mon with 6 perfect Origin Pulse Kyogres, etc.
And that way, there could be multiple quests one could tackle, and people might be working on different quests, instead of everyone trying to evolve a magicarp and catch 10 ghosts, ....