I am shocked that an adult would consider it creepy for other adults to enjoy their time on a Disney cruise. I love the characters and in my mid 40s. Would I keep a child away from seeing a character...Never! Disney cuts off the line at a particular time so it's up to the parent to make sure that they are IN line. It's not based upon who is in line in front of them.
Just like anything you get what you pay for! Disney is at a premium because of the quality they provide, the level of cleanliness and top notch customer service! They do not only cater to kids but also families of all kinds, even just two adults.
My partner and I have now been on 12 Disney cruises and expect to be on many many more! We enjoy our time and love watching everyone have an amazing time!