Do we still need to use `[...]` in Bash?

If don't care about compatibility, do we still need to use [...] in Bash? Many tutorial/book tell that [[...]] is more better/flexible than [...] e.g. [[...]] is support glob/regex, But today I still see many people prefer to use [...] as standard form, what is a reason behind this? What [[...]] can not do but [...] can do?

via Chebli Mohamed