Louis Davidson walks us through the case of the disappearing parentheses:
You will see the code is not the same as when I coded it:
Looking as this, one thing stands out to the eye: the parenthesis have been removed from the comparisons, but added to the literal value of 2. (Also, everything is surrounded by square brackets, but as awful as that looks, it is a common thing to see in code that is generated/parsed, such as this or a query plan.) When the person who wrote the similar code saw this, they were concerned it was wrong, then the next person who did a code review was also concerned it was wrong, and when I saw it, I was sure it was right, but only because I had a bit more faith that if this were a problem with SQL Server’s toolset, I would probably have read about it!
Read on as Louis explains the logic. My preference would be to retain the parentheses to make it easier for humans to follow.