Hello @ayek!
That’s a good idea that we went for initially. But we took it away cause it caused some issues that where to complicated to fix at the time.
We want to make this plugin as simple as possible for ordinary people. Since this plugin utilizes WordPress built in responsive image handling some people might change the max size without realizing what side effect it brings.
For instance the second largest size that WP produce is 2048px. A lot of people don’t know that so they might change the max size to let say 2100px which is not very effective. You will then have one image that is 2048 and one 2100.
One idea that might go along your suggestion is to add a checkbox that would produce an extra large size of 3072px. That’s double the size of 1536px which is one of the sizes that WP produces.
What would you think of something like that?