why do all the i2v workflows use hardcoded sizes
for ease of use you should (imo, at least) be using the source image resolution as it's not guaranteed that the default values you have set are within the same aspect ratio. it also means that the user has to manually change the resolution every time the input image is changed, which is insanity.
simply get the image res, scale down to 1mp then continue from there.
is there a benefit to having the width and height having to be set by the user like this?
both ways have its pro and cons.
If you have low ram you might want to generate at 832px - and want to keep same resolution that works for them
And if you have a square image, you might what to crop to a 16:9 etc etc
So thats why I opted for the resize node instead of the 1mb node. But that node also has its plus sides, such as those you mentioned
Could perhaps add both, and have a little toggle to choose. Will have in mind for sure ;-)