Some are, the intellij java community edition is even open source. The paid ones are not too expensive, I pay around 200€ yearly for the all products pack and that's definitely worth it for a professional developer. If you are a student or open source developer, you can apply for free versions also.
Gnome is great because of the large UI size. Like my 14" notebook has a roughly 2800x1600 screen resolution and it’s still pretty usable without any UI scaling. If the bars are an inch tall, you’re either using a huge TV or a screen from the garbage dump. Gnome really needs a modern system.