Game developers like to compare their engines like men compare dick sizes. Stick with what you know, many great games have been made with LibGDX and or other Java game engines, frameworks.
Java has gained a bad reputation over the years because of the low performance it had in the past, but it is not a bad language, it merely has a couple bad warts.
Not sure if I understood you correctly, did you mean to make “useful programs” with LibGDX? That’s probably not a good idea.