There are two prospectives here,
Scripting language makes implementation of OOP concepts little difficult. So, the main part, Object Repository will be difficult to implement and maintain using scripting language. But in case of OOP language like Java, you can easily implement POM (Page Object Model) and reuse your elements. It will make scripting breeze.
From business prospective, Selenium-Java is older than Selenium-Python. So, getting developers for Selenium-Java will be much easier and cost effective. So, business people encourage usage of Java. Hence making it more flavor day by day.
Hope my answer helped!