I'd also like to say not all commands work the same across the entire family of Maple or user created packages. A different definition may be used for the same command within another package. One may have carefully crafted a Maple document only to find out it breaks when loading a stray package on some brilliant new idea they might have just thought of. Similarily the sequence structure may be viewed differently when other packages are loaded.
I just believe it common practice to use some type of bracket in a sequence, be it a list, set, vector etc... not always a requirement but probably not a bad habit to get in to. Especially as Eric pointed out, if using them for any type of mathematical operation.