There is no reason for this increase except the fact that they know people are too lazy to migrate away.
They're not wrong. I'm a geeky guy with a tech resume as long as your arm, and I'd really rather do something else beside research how to export 1PWD data to something else, then import to $TOOL_OF_CHOICE. I'm sure it's not all that hard, and maybe that's part of the problem: it's monkey work, not an interesting technical challenge, right up there with "clean the gutters".
You can export the vault data (one export per vault) in a format that is largely supported by other password software to import. It's annoying but not terrible.