It is too late in development, but it is something that can be introduced post-launch.
I do feel like the developers are setting themselves up for a lot of headaches with fixed levels. For example, let's say Divinity does well enough to justify an expansion that allows players to continue adventuring with their old characters, going as far as pulling information from your old save file (games have done this in the past).
What level range does the expansion adventure start at? Is it aimed at Divinity : OS players that have completed every quest available in the original story? Or is it aimed at the players who focused only on the main storyline and skipped all the sidequests? What about the fellow who obtained a really high level by killing almost every NPC in the game?
Level scaling makes that challenge easy to address. Without it.. it's easier to make everyone start off with new characters.
That's not even touching on user generated modules.
