"Cats and dogs are all cute."
很 has a connotation that means something more along the lines of "very", while 非常 means "extremely"
Is 都 always necessary whenever you have an adjective that describes two or more nouns?
Even with or without 很, the description is equivalent; that says, the sentence can exclude "very" with 很, which is actually treated as "description link" or the substitution of "to be".
This is the first time the 都 construct comes up. Feels weird, it's an important one!