They don’t all consistently have actual half and half creamer at the grocery sections. They don’t stock a ton of each item, so availability can vary depending on demand. If people are doing a grocery order anyway, they are safer (and much cheaper) to order creamer as well as whatever milk they want.
As for the little shelf-stable creamers, any of them that survive unrefrigerated for long periods of time have a questionable relationship to a cow at best. Even the ones that claim to be actual milk or cream are generally more chemical than dairy product, other than the much more expensive UHF type boxed milk, which I’ve never seen in any Disney room, quick service or food court. My opinion of their creamers is based on the fact I have an intolerance (mild allergy) to non-dairy substitutes, and cannot use Disney’s unrefrigerated creamer mini-tubs without drastic results. And the “creamer” dispensers at the value resort food courts are even worse, no cows were even remotely consulted on the production of that substance. DH has learned to put up with the wait for me to hunt down real milk from a CM at the food courts, it’s better and safer for everyone involved.
If you aren’t picky about what coffee you drink or what you put in it, and you don’t have any dietary restrictions, yes, there are always or mini-tubs of creamer or the powder packets along with the coffee supplies at each resort. And there’s generally sugar and sweetener packets and stir sticks. But if, like me, you’re fussy enough about your coffee that you have a coffee maker and supplies in your Owner’s Locker and you’ve created a whole thread on the DIS about what type of coffee maker is at each resort, you want to order (or bring) your own coffee and supplies.