None of that impacts the actual player race in terms of quality, that’s all world building. I think it’s great that Gnomes have finally gotten some story and development.
My issue with Mecha-gnomes is that the base gnome model has simply been hacked together with mechanical bits. The arms and legs look great, but you can’t even transmog armor over them, which doesn’t help the fact that the base Gnome model is hard to transmog with due to texture compression. The head options are a little lackluster and the racials aren’t terribly interesting, they’re just good. There’s also only like 3 options for feet and hands each… Compared to the potentially hundreds (and increasing) transmog options for those slots.
Vulpera at least got a complete texture, several interesting racials and can still transmog everything. They were also highly requested, unlike Mecha-gnomes. They feel like an actual, separate race and not just a subset of an existing core race, unlike many of the other Allied Races.