So originally, I intended to just forget about suggesting the Lupin as a playable race because I didn't think the devs would ever want a playable beast race in FFXIV. However, since they announced the Hrothgar I'm going to take that as a sign that they support the idea, as long as it doesn't ruin the story, lore, or various other aspects of the game.
The main reasons I wanted to suggest this race, apart from just being a beast race, is their size. The Hrothgar are obviously going to be about the size of the Roegadyn. However, it would be nice to see more "size versatility" with the beast race. Many players like playing different sized characters, small lalafell, average Hyur, slightly short Miqo'te, the taller Au'ra, and the bigger and bulkier Roegadyn. Looking at the Hrothgar Video, it would make sense that the race would use the armor models from the Roegadyn. That being said, I would love to see a beast race that uses the more average sized clothing. A perfect solution to that would be the Lupin. They are sized off the Hyur, meaning that Hyur armor models would fit them. It also means you wouldn't be a huge character, which while some people like, others might not. Basically, I'm suggesting an average sized beast race.
Secondly, *from what i know*, the Lupin as a playable race would be lore friendly... or at least not against the lore. The Lupin lore is a scarce since they are just some side characters and enemies in Stormblood. However, from the lore it seems they don't have a Primal. That lines up nicely for a primal-slaying playable character. They're also servants for many people in Doma, which means they are accustomed to helping people. After Doma was subjugated by the Garlean Empire, many of them dispersed throughout the world, a couple stayed, and the rest were put in the Garlean Military. At the beginning of the main story, I arrived as a lone adventurer wth no past, and no set future. As a Lupin who ran away from Doma, this would line up well. It would also be cool for new players to learn about the lore of their people when they reach the Stormblood content like other races learn at various points of the story.
Lastly, I think the Lupin might be a bit easier to add in as a playable race then just creating a brand new one. The models and textures are already in the game, the only thing they might have to add in is some customization. I think the most they would need is eye color, hair color, and maybe ear and tail size to just go the extra mile. Other than that, the body, head/face, and armor are all in game already. Now honestly, I was planning on playing male if they did, so I wasn't really considering the potential female version. I'm also sure that if they released a second male only beast race, it would get some backlash. So while I've said it was easier to add in since it's already in the game, that doesn't include a potential female version.