So much of this depends on your own viewpoint and circumstances. Personally, I would and will always crate train any dog I have. Even if they don't end up using it much, I would still crate train. My reasons:
1) as a puppy it's easier to confine (though, yes you can do it with an expen too) - for potty training, short time-outs, AND for their safety.
2) safety - whether it's a crate, expen, a specific room in the house, I believe in confining a dog when you're out of the house for several reasons (i) their safety - they can't tear things up, swallow things they shouldn't, get tangled in/ caught in things, etc. if they're confined (ii) if there's a fire or someone breaks in (or just opens the door without remembering the dog might be right there) you have a better chance of them NOT running out/ getting lost (and in case of a fire, you know exactly where in the house to find them)
3) Feeding - especially if you have multiples OR if they're messy eaters
- Perry eats in his crate sometimes, especially in the morning when I go to work and when we're in the US (there are 2 other dogs in the house there) - so that I can do other things while he eats -- yes, you could do the same with an expen.
4) if they will ever have to go to the vet for an overnight, you have a dog that is used to a crate and having to be in a crate isn't one more thing to cause stress in an already stressful event
5) if you have guests who are afraid/ allergic/ or just things going on at home, it's good to have a space where the dog can be calm and quiet (and better to crate train BEFORE you need it than wait til they're older and realize you need it)
6) if you travel (or plan to) - better to have a crate they can stay in in a hotel room (or worst case scenario if they have to travel in the hold of a plane - you may never plan that, but sometimes things happen - like the current COVID situation, some airlines are not allowing pets in cabin though it seems they're returning to that) - especially if your pup ends up being a chewer or has anxiety, it's better to have a crate where you can leave them in a hotel room instead of worrying if they will cause damage (and hurt themselves) OR that the housekeeping staff will ignore the "do not disturb" sign that you put on the door (or that you forgot to put on the door) and opens the door, letting a scared dog run out in a strange city. Same thing on travel - what if you're visiting friends/ relatives and they're not as enthusiastic about puppy running around, chewing on things, etc. especially when they're / you're not home. better to have an option to keep them in their crate.
I'm sure there are a few more reasons, but those are the main ones. Overall I think it's good to have options, even if you ultimately decide not to use them, especially for safety.
Perry sleeps in his crate at night (for the same reason as Ricky and Popi - for us Perry is a restless sleeper and none of us would get a good night sleep if he was out) and stays in his crate when we have to leave the house. That usually isn't for more than a couple of hours. If we had to leave him alone for longer periods regularly, I would consider either a bigger expen OR a small room in the house where we could remove most things (or I'd get a bigger crate to give him more room). He doesn't love his expen, but because he eats in it he's good with it, especially when we're on a schedule. He's less happy with it but goes in and curls up, when it's off his scheduled time.
Just a side note on anxiety/ leaving them out - all dogs are different. My last dog (a dalmatian) would get MORE anxious if I left her out in the house or yard when I was out of the house than she would if I left her in her crate (it was her safe space and she'd curl up and relax there).