Why? If you're doing things correctly, you don't need to specify data types particularly often in SQL. You specify it once when the table is created and that's it. All you care about on the programming interface is that your application knows what data type of your language to use with each data column. What's wrong with a verbose and descriptive name for a data type?
I don't think they're saying that having verbose name is dumb, I think it's that a type called "timestamp with time zone" doesn't actually store a time zone.
SQL data types have some verbose names, like "NATIONAL CHARACTER VARYING (20)". PG adds a "TIMESTAMPTZ" as alias for "TIMESTAMP WITH TIME ZONE" (which I'm not sure whether is a sql ansi standard type or just convention).