I fail to understand why the EV could not be interactive, it is not the working out and changes that have to be checked by the software, only the final version. In the current interactive puzzles, each square must be checked to see if it contains the correct letter, if the solution requires a number, Greek character, or more than one letter, the contents of the box can still be compared with the correct contents. In the same way as a cell can be chosen to ask for a letter hint, a button could be added to the bottom of the screen to shade a square, (or unshade it). All of the current interactive puzzles can be printed so where coloured pencils are required, the puzzle could be printed off before completing and scanning the grid to enter.
I understand the altruism of people that have won pens not entering again but the number of entries is the only reliable way the management have to know how many people are looking at the puzzle; if they feel that too few people are reading a certain page then it is time to replace it with something that may attract a larger audience. I have never worked in media but would guess that the more entries they receive, the more they can charge for advertisements on surrounding pages.
As, currently, the Giant General Knowledge and Herculis puzzles are non-interactive pdf files, are they too going to disappear.
The weekly just-for-fun clue competition has just been closed in the puzzles newsletter and, according to that newsletter, there are going to be more changes coming in 2022.