Pill bugs: beneficial pruners or garden detestation?

I'll add to the topic.  I've definitely seen pill bugs eat seedling with no slug pressure around and I have a lot of them due to surrounding mature forest.

They search for moisture and come out any time humidy / temp / rain affords. I've not found a good way to "deter" besides timing or transplanting rather large plants. I time all seeding with rains and they basically ignore the live plants while they sprout.  Gobs of pure mulch or tree litter seems to breed them.  Turning soil seems to kill. They will attract to humid plant (strawberries for sure) and feces material.  

I've been making mini hugels for pill bugs Uphill from  planting spaces that need organic boosting. So far it seems to be working extremely well! I anchor the spot with a thick branch for the bugs to hide under when there's lack of rain

Pill bugs DO & WILL eat small seedlings. I have seen them on my lettuce seedling, had one destroyed by them and had several young marigolds completely destroyed by them. They were in eye sight crawling all over young  healthy plants until they destroyed them. This was run as an experiment to see if they would attack young healthy plants. They did. If you have them in large quantities, use soap water ratio 1 tablespoon to a gallon and spray your plants in the soil around them with the soap water. I do this twice a day. It gets into the pill bugs exoskeleton and causes it to suffocate. You do not want to protect the cute sweet little pill bugs if they are in large quantities. They will destroy Young plants.

I don’t have much damage.
My regular regimen is:
Interplant veg with petunias, marigolds and nasturtium
Add a radish seed or two to squash and cucumber hills. Don’t pull them - let them go to seed.
During slug season, of course, shallow dishes of old beer. Cover with a little chicken wire to keep the dogs from drinking the beer. Anchor the chicken wire with old knitting needles.
Plant herbs liberally amongst  berries and veg. Especially oregano and thyme.
Sprinkle  diatomaceous earth now and then.
Never water late in the day (it doesn’t rain here in summer, so watering time is easy to control).

Sure I lose a few berries and sometimes have holes in greens.  But mostly it’s  all fine.

Except for basil. I have never succeeded with basil unless I grow it indoors. It’s always full of holes. Any tips?

According to Pascal Badaur, their position in the ecology is "meal".
Though I believe his book and others disagree about which variety - pill, or non pill - are edible.  One variety is a millipede, which is inedible... you'll look it up anyways.

As for eating seedlings, the contest seems silly to me:  if they prefer leaf litter, then likely it's just our all too natural tendency to clean up our gardens - cleanliness is only next to godliness in medicine and... something witty.  Give them leaf litter to eat and they may not bother with your seedlings to any large degree.  If the population explodes, you probably just killed all your centipedes and ground beetles etc. etc.

As far as I know pill bugs are a fun thing for kids to play with.

I have never seen them attack plants.

If you are having that problem I hope you find a solution.

Try salt, vinegar, and a soapy solution.  Soap and vinegar work for me.  I have not tried salt except for the kind of pest found in the kitchen... as in flour, beans, etc.

Yes, I have absolutely observed pill bugs taking bites out of my plants, young and old.  Generally, though, I've not observed them to be so bad that I lose an entire plant, as some in this thread have bemoaned.  Maybe I am just lucky.  One year, however, I experimented with letting my tomato plants sprawl on the ground as opposed to staking them up.  The tomato plants were perfectly happy.  They thrived and grew wide just like sprawling squash vines do, and they put on tons of fruit.  And pill bugs ate 90% of the tomatoes before I could get to them.  Never again.

So, I absolutely believe that pill bugs can predate on your veggies.  But when following typical gardening practices, I've not found them to be an excessive pest.  Besides, in a permaculture setting - rich soils, lots of mulch - there are just sooo many pill bugs that I can't imagine trying to fight them with any hope of success.  Just learn to live with them, somehow.  Of course, I say that because, at the moment, they aren't eating me out of a harvest.  I am totally willing to believe that at different times in different places they could become in intolerable problem.

I have seen pill bugs on leaves with bites missing quite regularly. There were also slugs in those gardens.  I have never gotten out a magnifying glass to see if the pill bugs were eating the leaves, or just enjoying the slug slime (or more likely the edge of the leaf that starts to decay the moment the slug eats part of it). In places where I have managed better slug control (but not bothered trying to limit pill bugs) the leaves are not eaten save a very few tips of leaves that I think birds nipped while grabbing a bug.  

That said I have lots of (wild, native) birds with access to my gardens such that the pill bug numbers probably stay on par with the dead and dying vegetation.