That said, is it really normal to expect to be able to return a non-faulty product once it's shipped, or unreasonable of Dell to refuse such returns if they don't want to sell on that basis?
In my country (the UK) there are consumer protection laws that include various rights to return goods purchased remotely for a short period even if they aren't defective. In principle, these are supposed to allow for not being able to inspect the actual product the way you could in person if you bought from a store. However, for better or worse, business customers do not enjoy the same legal protections as private individuals, and a lot of potentially one-sided terms that would be unlikely to stand up in a B2C context because of statutory protections seem to be routine in B2B sales.