The big limitation in my eyes is pvp, twinks queue separately.
I had to switch xp back on to access some content, shadowlands I think.
Other than that I love twinking.
From what I understand, if you like cosmetics and you missed something from pandaria last time then its good.
I'm sure other people will have a different opinion.
I'm not wasting my time, if it was a permanent new way to level then yes I would.