There's a saying somewhere in the game industry that artists should be able to get their assets into the game itself asap to view changes. One of the solutions is live reloading their models/textures (imagine export->alt tab to game and see changes).

However, I did note that casey processes his assets into bundles pretty early in the pipe, thereby putting in an extra step, possibly increasing process times/introducing more work when the number of assets increases. Wouldn't it be better to implement live reloading of assets first, then combine it with asset processing later? Or would the load times be just too terrible?

I think Casey already addressed this topic, but as a quick summary: there are no artists working with the game on a daily basis; so there's no point in implementing features that won't be used.