It has already been suggested that BLOCKS be able to be hidden, and the response to this suggestion was that CSS can be used to hide blocks at runtime. That is true.
However, when it comes to hiding specific elements, things get a bit messier. Unlike having blocks visible in the designer but not rendered at runtime, having hidden elements is much more difficult to deal with from within the designer. There may be times when elements are still under design and have not been finalized. The designer may wish to hide those elements in ALL scenarios (not just desktop, tablet, etc.), BUT ALSO HAVE THEM HIDDEN ON THE DESIGN SCREEN. This is where using CSS is not helpful. While the element can be hidden at rendering time, it still appears within the designer, making it difficult for the designer to work with a version of the website as it will be viewed by the end user.
If the issue of physically hiding blocks/elements from ALL views is that they will not be visible (and therefore not locatable), this can be solved by still showing the blocks/elements in the navigation area (Blocks & Outline view). Having an additional right-click menu selection to Hide/Unhide the block/element solves the issue from the designer's perspective. In fact, taking this a step further, the act of hiding/unhiding the block/element in the navigator pane should result in the CSS being generated automatically.
It has already been suggested that BLOCKS be able to be hidden, and the response to this suggestion was that CSS can be used to hide blocks at runtime. That is true. However, when it comes to hiding specific elements, things get a bit messier. Unlike having blocks visible in the designer but not rendered at runtime, having hidden elements is much more difficult to deal with from within the designer. There may be times when elements are still under design and have not been finalized. The designer may wish to hide those elements in ALL scenarios (not just desktop, tablet, etc.), BUT ALSO HAVE THEM HIDDEN ON THE DESIGN SCREEN. This is where using CSS is not helpful. While the element can be hidden at rendering time, it still appears within the designer, making it difficult for the designer to work with a version of the website as it will be viewed by the end user. If the issue of physically hiding blocks/elements from ALL views is that they will not be visible (and therefore not locatable), this can be solved by still showing the blocks/elements in the navigation area (Blocks & Outline view). Having an additional right-click menu selection to Hide/Unhide the block/element solves the issue from the designer's perspective. In fact, taking this a step further, the act of hiding/unhiding the block/element in the navigator pane should result in the CSS being generated automatically.