I think it is "nice" e.g. to adopt/get littermates etc. as TWO kittens, and SOME cats might appreciate "company", introduced at a later stage... but MANY don't! I don't think it's CRUEL that an Adult Cat be "solitary". I think it is entirely possible for an "owner" to provide sufficient company for any cat - Even in full-time work. I think felines simply "shut down" (sleep!), without stimulation, and don't feel "loneliness" in quite the same way as humans. And you can make the VERY BEST of the time you are together with your Cat, whenever you are home!