Idea Summary
Currently, editing columns in APEX is possible only by loading the entire form page even if we want to modify just one column value. Instead, allow read-only forms to have its columns editable by clicking on them to put the column in edit mode to edit its value “in-place” quickly.

Use Case
Contemporary web sites like JIRA allow us to quickly edit individual columns in-place without having to load the entire form to edit just one column. User should be able to edit any random columns individually by just clicking on them. This adds to better UX and user-friendliness to quickly edit a column value without overwhelming the user with a full-blown form comprising of all the columns of its underlying table/s. You can check out JIRA as they offer free account with 10 users.

Preferred Solution (Optional)
Read-Only forms should have their columns editable by clicking on them and after done with editing, user would click the column's icons to either Submit (check mark) or Cancel (X) the edit. Accordingly, the read-only columns would be configurable as for their editability/authorization in the Page Designer to render them as tiny “column-forms”.

If we can accomplish something without having to opening another page or modal, do it in-place with the shortest click-path and the quickest action to save user's time and productivity.