- WYSIWYG editors are bad about making small unintended changes that can easily slip by undetected (Interface Builder in Xcode for example often changes XIBs/storyboards just by viewing them)

- WYSIWYG editors bury bits of configuration in inspectors that are only visible in certain conditions, e.g. a control being selected, making them less evident and more difficult to find

There are circumstances where I think they still work alright — for instance I still enjoy building Mac apps with XIBs in Cocoa, but there’s a reason for that: traditional desktop UI has much less of a need for flexibility and generally speaking, has far fewer moving parts since it doesn’t have to hide things as a result of limited screen real estate. Additionally, these apps will only ever run on Macs which further reduces need for flexibility/adaptivity.

For mobile and multiplatform on the other hand, I strongly prefer code. It just works better.