i personally would sail with disney (when i can afford it) with or without my kid. of course, she is young so if we do ever get a chance to sail within the next several years with her, we will. but i can totally see myself sailing on disney (or going to disney world/disney land) with just my husband.
i am just a huge disney fan. and i know a lot of adults who love disney.
as far as more commercial-like vacations, disney has always proven to us as being top notch with customer service. i would think their cruises are also top-notch in this area (of course, not being on a disney cruise, i could be wrong - but going off other reviews, it seems to be pretty consistent with all things disney).
as far as the OP, yes, certainly up to their opinion - to each his/her own! but for me, i would have to respectfully disagree.
anyway - anything to do with disney, one should expect line-ups. it is just the reality. i don't love it (who does?) but it is the price to pay for disney fans of any age. this is especially true with character meet and greet. i don't know if the cruise has character dining? if so, it's worth it even if it costs more.
i know with disney world, we never line-up to meet characters anymore. we choose at least two character dining experiences when we vacation at disney. that way, the characters come to our table. it's the best way to go! plus the food is good - and well, we had to eat anyway so it killed two birds with one stone.