I agree in some extreme cases but the Wizard of Oz group doesn't look abused or cruel imo. They just look well trained in "sit", "stay", are clean, well-fed, exercised, healthy and groomed, as they know they'll get a treat because that's how training goes...and it's only for one day a year. Same as dog shows. Responsible costumes tell me that the owner really dotes on her dogs and loves them to pieces. The dogs may enjoy the attention.
I've never dressed my dogs up because it doesn't give me pleasure, but I don't fault owners who often (with exceptions), turn their world around 24/7 just to accommodate their pet's needs, desires, Vet visits, pet-friendly travel plans, etc. fenced yards, etc. They deserve one day of self-entertainment
I do feel bad when I see a costume that looks very uncomfortable or they've spray-painted their fur or faces. But if I see dogs dressed up responsibly and only for a one-nighter, I give the owners a pass. I choose my battles as there's much worse "abuse" to focus my energy on.