You make a good point. There are a lot of great Minecraft mods out there even now, but even in the mods, combat in Minecraft is plain awful. There's only so much you can change with a mod before reaching a point where (I believe) you should just start over.
I don't enjoy re-inventing the wheel, but it's scary to think about putting so much effort into a project only to eventually hit a wall where the base platform just doesn't offer what you need. I feel like it's time to break away from relying on the Minecraft engine. It's buggy and I'm a fan of native support rather than relying on Java.
Perhaps this still seems unreasonable, but at the end of the day I want an engine with fully exposed source code and completely under my control. For example, say I wanted to make a voxel shooter game next, or a MOBA, or a tower-defense game. I could easily tweak and re-use my engine, whereas trying to get Minecraft to suit these needs would likely result in unacceptable latency and some awkward "hacky" solutions.
Financially, I know mods can do fairly well for themselves, but I still think it's unfair to continue supporting Minecraft. Honestly, I feel that the mods have far surpassed the original game, and that the original game was quite lazy.