Yeah. I don't really dislike the idea. I was more annoyed that Lucas renamed it to Indiana Jones and the Raiders of the Lost Ark, because I considered Indy one of the raiders.
Benefit, the subtitle won't spoil anything about the McGuffin. The last title was a mouthful, and the short, less pulpy title will distance it from KOTCS. It could make the movie seem grittier, which it probably will be under Mangold. A poster with just Indiana Jones on it could look pretty cool and iconic.
And the marketing people will love it and see it as opening the movie up to new audiences, rather than sounding like a sequel. Which, again, seems in Mangold's style, because both his Wolverine movies felt mostly like stand-alone movies from either themselves or the other X-Men movies. And if this movie really feels like a fresh start and a change in tone, under a new director, giving it a title that sounds like a first movie in a series might be appropriate.