>>48328134None of them are really "main features" outside Alolan Dugtrio and Mr. Rime, who is already human-based to begin with.
Galarian Weezing is meant to be industrial chimney's but since it was the galar region, aka, British, they decided to add the mustache as a compliment.
Otherwise I think it's just a coincidence they ended up being on alt-forms.
Besides, your exaggerating a bit, don't you think, the percentage of new forms isn't that big when you consider the rest like Rapidash, Sirfetch'd Cursola, Obstagoon, Runerigus and all the rest.