There are more holidays in real life than there are in WoW.

With that said, most of the holidays WoW borrows inspiration from are single day holidays, but, out of necessity, WoW extends them to multiple days. (Often a week or more) This can make them seem crowded on the calender, but it's not as bad as you seem to imply. The longer duration can result in the exact opposite of what you say: Instead of spending too much time playing to complete everything in a very limited time frame, you can spread things out over the duration. Yes, there are some poorly designed aspects, such as the "collect every mask" achievement for Hollow's Eve and the horrendous candy bag drops during Love is in the Air, but those instances are few and far between.

I, personally, find the holidays quite enjoyable and look forward to the new and improved Noblegarden. If they really are that stressful for you, maybe you should take this holiday off. After all, it doesn't count towards the proto-drake. That, of course, is entirely up to you.