Autograbbers also negate the animal friendship points you gain by doing it manually...
This is true, but let's look at some numbers...
Goats produce every other day. That's 5 friendship points every 2 days, and you get 30 for petting them in that same time. If you're a Shepherd, now you're looking at 5 from milking per 60 from petting. So without Shepherd, that's like an extra petting every 6 days, and with Shepherd it is like an extra petting every 12.
Sheep produce every 3rd day. That's 5 friendship every 3 days, and you get 45 for petting in that same time. If you're a Shepherd, they produce every 2nd, so that's 5 for every 60, like the goats. (I will also argue that by the time the sheep produce faster from high friendship, you should no longer be concerned with friendship because you're already at 4.5 stars out of 5, nearly maxed out.) So without Shepherd, that's like an extra petting every 9 days, and with Shepherd it is like an extra petting every 12 again.
Cows is where the numbers don't look
quite so disparate. They produce every day, so without Shepherd, that 5 on top of the 15 for petting means an increase of 33% to the amount of friendship you get daily. That's an extra petting every 3rd day, but with Shepherd, it turns into every 6 days. So at least with cows you know they're producing every day, and you won't waste time gathering production that isn't there... and the increase is above 20% in friendship gained, but if and only if you aren't a Shepherd. (And yes, I know not many folks are Shepherds. Artisan just seems a waste to
me, since money becomes a non-limiter after not too terribly long.)
For me? That teeny, tiny, little bit extra is not worth the extra time, effort and the frustration when you go to milk goats or shear sheep that didn't produce that day.