The alternative is frankly much worse: without a VERY generous physics setup, you just get stuck in the terrain all the time. This is due to Unity's worthless, worthless physics engine (which is obviously tuned for racing games and not for moving around in tiny congested spaces). It actually worked a lot better five or so years ago and then starting with "Unity 5" they shat all over themselves and everyone was constantly getting stuck everywhere, so I implemented the current workaround. I haven't looked for better workarounds in a few years and it's on my list to do, but frankly it's not at the top. I'm more concerned with synching animation to movement, that's something that can and will be improved. As for water, we'll work on it when we want to do more with it. Right now there's not a lot of underwater content and not a lot of plans for more underwater content, so there's no reason to focus development time on underwater movement.