Package ratings are a great way of getting your app ranked. The first and most important thing for a new app, is to get ranked on keywords. This can only be done by getting ratings, or wait for months to get those tiny amount of organic ratings.
If you aren't ranked on any keywords yet, but you app ins't new, these installs will still get it ranked.
You can also use just package installs combined with Ratings and Reviews, to make your app looks more appealing to other people.
Better category rank
You probably won't benefit much from a good category rank, since you're going to need a very high number of installs to high some high ranks.
Overall higher keyword rankings
Package installs will help you app getting initial keyword ranks, and give a little bit towards all the potential keywords you're having in your title, description and keyword areas.
The perfect way to get your app started
We recommend starting with package installs, for the first month, if your app has just hit the app store.
Have a look at our ASO service, this will give you a head start, compared to you opponents.