I'll tell you what people who actually understand something about Java mean when they say Java sucks:
>Java is terrible* for anything remotely resembling realtime applications. That means a program where dropping inputs or processing them in irregular timings would be catastrophical. This is usually the case for stock trading bots, but could be reasonably applied to any twitch shooter where a drop in FPS could completely break the game. Minecraft ain't twitchy and it already suffers a lot from its stuttering. Nobody cares if a VN or roguelike drops a frame from time to time, and even then, it's unlikely, considering they are far from resource intensive, so even if the GC kicks in, you will notice nothing
By terrible*, I mean you can get around these limitations by knowing the JVM well enough to avoid triggering the GC too much. Still something you better not use for the control system of a plane, but fine for most non critical applications.
>The JVM is heavy and takes way too long to boot up, even for programs that should boot up instantly due to their actual size.
Not an issue, considering most games nowadays take up to 20 seconds to boot up and people kind of expect it already. It's also something you only boot up when you have a lot of free time ahead, and sonething you don't constantly close and reopen.
>The JVM has had its fair deal of vulnerabilities.
Only memesters around here actually uninstall Java in their home computers due to this reason. Thing is, for most security setups, if you get to the point of a program going rogue and executing a malicious JVM program, said rogue program probably could do the malicious stuff on its own without overengineering the exploit that much.
>Java, as a language, sucks
This is true. Java is showing its age already, and even though Java 8 tried to modernize it a bit, some of the stuff it asks you to do some really simple stuff is mind numbingly obtuse at times.
>Java libraries, and specially community made Java libraries, suck hard
They really do. Most Java libraries are overengineered due to some dumb OOP practices they teach along Java in colleges. That said, it's not the case for libgdx. Libgdx is great.
>Java tools suck
They do. I dunno why they insist on making bloated as fuck Java IDE in Java, but they do, and they are never without terrible bugs. Chances are you will never ever touch like two thirds of the options and modes Eclipse has. Chances are you won't even understand why they are there. And Eclipse isn't even the most bloated IDE out there.
Also prepare your angus when you get to actually using Maven and Gradle. Boy do they suck at cache invalidation and not failing randomly.
So, if you are feeling particularly masochist, making a game in libgdx is fine. If you aren't, take a look at LÖVE2D, which is even simpler than libgdx.