Nope. They're not too cramped so long as you buy one that is FOR a large breed. Make sure they can sit, lay down, turn, etc comfortably before buying.

If there's no other reason than wondering if they might prefer it though, I wouldn't waste your money. None of my dogs sleep in crates.

Yes, you certainly can! They come in handy a lot if you want your dog to stay or sleep in the same place or if you spill something and don't want him to get into it. Some dogs really even find their crates comforting and reassuring, like their own room that nobody else can enter into. I would definitely look into buying one, you just might want to make sure your dog is comfortable with being in one. It makes some dogs very nervous and scared. Also, make sure your crate is big enough for them to lie down comfortably but get one small enough so that he feels secure and also he won't pee it. Also it would be helpful to put a dog bed or fluffy blanket inside the crate.

We've had dogs for over 40 years. Never owned a crate as they are considered unnecessary in this household.

I prefer the exclusion method. If a dog is not compatible to the household it gets turfed out into the yard until it is. In three years my dog has been 'invited' to an outdoor timeout 3 or 4 times.

My dog does not come running for kitchen spills - he does not molest our company - he knows where he can safely sleep.

I have two Mastiffs. The older of the two is three; he is not crated. The younger of the two, who is about a year and a half old, is indeed crated. He's crated for an hour after each meal to force the two dogs to relax separately (this is to reduce the risk of bloat). He used to be crated at night and whenever he couldn't be watched, but he's maturing nicely. Because both dogs have proven to be trustworthy with free run of the house, neither of them are crated overnight or in our absence.

Yes, there is plenty of room in the crate, when he is crated. You need to buy a crate that fits the dog, obviously. Because mine is a giant breed, I have an XL crate. It's, what, 54" long? It's like this:
http://www.pawz…
He has more than enough room to sit and stand up. He can easily turn around and can lay down in various positions. Because the crate is suitable for his size, he isn't at all cramped.

As for your situation, no, a crate sounds unnecessary. Crate-trained dogs should love their crates, yes, but dogs who aren't crate-trained and who do not need crates won't really benefit much from them. They might like the cozy atmosphere, but unless your dog displays anxious tendencies (in which case he would benefit from having somewhere safe to hide), then I'm sure he's perfectly fine sleeping on his beds instead.