Wow, this topic got huge!!
On the crating issue, I have to say that I would find it cruel in some circumstances... not ALL circumstances.
I'm lucky to have a busy household with someone home pretty much all the time, people I can trust always around, and an easy time finding someone who knows both the dogs well to come watch them in case we should ever have to be gone for very long. A lot of our friends still live with their parents, or in crappy apartments, or don't always get along with their significant other at home, etc....and prefer to come by our house and hang out to staying at home. We don't mind at all, as long as they're not disrespectful of our house. We've had several friends turn into temporary roommates because their home situation changed and they didn't have anywhere else to go, and asked us for help. Actually, Moro was sort of "accidentally" socialized because of this lifestyle -- she sees all of our friends coming by on a regular basis and has observed this since she was a puppy. As a result, she is very friendly with all of our friends...she is a little wary if she's meeting someone brand-new who's never been to our house before (especially if it's a guy, she's a little more timid around men), but once we introduce them to her and let her know they're okay, she tends to accept them quickly. And she LOVES anyone who spent a good deal of time with her as a puppy... we had a friend living with us for a few months at the time we got Moro, she was having some pretty serious abuse problems with her boyfriend and had nowhere else to go for help... she was around Moro from the time we got her at 3 months, till Moro was about 6 months old, when she (our friend) got her life straightened out and moved into her own place. She still comes by to visit us from time to time, and you can really tell that Moro remembers her from puppyhood - she becomes totally silly as soon as she sees her, even if it's been months... wriggling all over and wagging her tail and trying to lick her
With Midas, it wouldn't be as much of an issue because he is less excitable and destructive than Moro, but he's also a puppy and she's sort of like a big sister to him... he follows her, wants to know where she's going and what she's doing, and wants to be involved in whatever she's doing. So if we left Moro alone and she started destroying stuff, he would probably be eager to pitch in and help
We never crated Moro at all... she was not socialized and had only been with her mother when we got her, and was scared to death of all people... we didn't want to encourage that by locking her in a small space. And yes... she destroys stuff occassionally. Our carpets, a few spots in the hardwood floor in the bathroom, and a good population of our shoes will never be the same again because of her
... but we just kept at telling her "no" when she chewed on something inappropriate, replacing with a toy, and now she will choose a toy over destroying something of ours. The only thing we've had trouble getting her to stay out of is the garbage, but she only gets into it every once in a while, usually while we're asleep, or on the rare occassion that no one is home. I'm not going to start locking her in a crate when no one is home because of this. We will either find someone to watch her, or trust her to have the run of the house while we're gone, and be willing to clean up after her if she decides to destroy something while we're gone.
Midas was crated at night during the first week we had him. We had to borrow the crate from a friend... He came home to us covered in fleas and ticks, and we spent a long time tweezing them off him, but we still had only made a dent in their population... we kept him crated to keep him seperate from Moro during that week so that she wouldn't get bugs from him. He went to the vet the next day, and we kept him crated for 4 days after that (NOT continuously, just while we were asleep) while the vet bug poison worked to kill the rest of the bugs on him....we didn't want Moro to be licking him or getting dead ticks on her. After that, we cleaned the crate out and took it back, and he has the run of the house now. He is a perfect foot-of-the-bed dog...he loves sleeping on my feet
He did NOT like being in the crate at night, and I felt bad for having to do it to him, but it was necessary at the time.
I would say that people know their individual dogs and what works for them, and what doesn't. I would be a little iffy about someone leaving a dog in a crate for 8 hours or more every day... but that person knows their dog better than I do, and there might be no other choice. Some dogs do okay with crates and see it as their 'safe haven', others I would consider it cruel and you can tell they definitely don't like being confined. I don't think you can just look at it and say "all dogs who are crated for more than x amount of hours daily are being mistreated", it really is an individual thing. If I tried to put Moro in a crate right now for 5 minutes, I would consider it being cruel, because she's not used to that at all. Some dogs ARE used to it though, and will be okay as long as they get plenty of love and attention when their owner is home.