For drop-in guests, I don't think it's necessary.
If you're inviting people over for dinner and after dinner coffee is a normal thing culturally, it's nice to have but not required.
If you've got overnight coffee drinking guests, then having coffee available is good hosting.
As an aside - if you're offering instant coffee, make sure you offer it as instant coffee, rather than just saying "cup of coffee". Some coffee drinkers don't mind instant, for others, it's like being offered a coke, and getting a diet caffeine free generic cola, or being offered a beer and getting a non alcoholic beer, and they'd prefer to say no.
As another aside - one alternative to keeping instant on hand is the little single cup filters. One tiny filter fits over the cup, and you get a fresh brewed cup of coffee, without having to stock the instant stuff, or coffee making apparatus. They're individually sealed, so going stale is less of an issue than with regular coffee grounds.