I guess tiling window managers should be considered more of a specialized niche tool, and in that it is commendable that i3 does such a good job of it. I do really admire it for being so light-weight on resources compared to a lot of the other more popular WMs. I say a niche tool because I've never really understood why someone would prefer a Window Manager that places a lot of constraints than one that lets you cont…
While I kind of get where you're coming from, contrary to what you describe it's actually more control for me personally. What you call constraint is my preference that I'd otherwise have to handle manually. Sizing is more convenient than what I did before (basically manually adjusting everything to the tiled views, I prefer that both for basic layouts and keybinds or fiddling with the mouse). Plus, at least with i3, you can always bind something to enable floating mode for a particular window if you really feel like it (in practice I rarely do that anymore honestly).