Darth as a title sounds cooler than “Darth” being Vader’s first name.
“Darth, we must talk.” Just sounds kind of silly. Rhymes with Garth.
But, having a bunch of other dark side Force users with “Darth” as a title/name, along with a red light saber, makes Darth Vader less unique.

Grevious’ cough was another thing I disliked, because, like the above, it makes Darth Vader less unique. Here, we also have an asthmatic cyborg villain. Plus, despite all the crazy CGI robot kung fu, this coughing and wheezing video game villain didn’t seem that threatening. The cartoon version was so much better.