If you had actually read any of the responses to posts about this very thing you would see why this is a very tired and loaded question. This has been answered over and over again.

Yes, the devs are slow with updating. No, I am not sticking up for them. It's a bugbear for fans so much as it is for those who prefer having content constantly fed to them. HOWEVER, the fact that tens of thousands of people are still finding enjoyment in it means that to those people it's still worth playing. This shouldn't be a "surprise". It's clearly fulfilling a niche in gaming that few other titles have. It appeals to a particular play style and player and they don't need to justify why they enjoy it.

It's easily one of the most replayable games on the market at the moment, even in EA format. But again, if you're just wanting to fight new mobs and conquer new biomes/bosses, then you'll probably be disappointed.

You can find what the developers have changed in their updates and see for yourself. If that doesn't appeal to you, then don't play it again. Easy.