Putting a straight-party checkbox on a ballot violates a key design principle: The polling place and ballot should strive to avoid steering people toward specific choices. This is also why some places randomize candidates’ names or stick with alphabetical order.
The human brain would rather work on auto-pilot than think carefully. Give it an excuse to stick with auto-pilot, and it’ll happily do so.
Even if that means outsourcing your vote to the people who chose the slate and designed the ballot.
You can choose to vote a straight-party ticket, but the ballot design shouldn’t influence you to do it.