As much as I love the uber right-click menu, switching between different brushes is just more fluid with keyboard hotkeys.

In ZBrush or PaintToolSAI, you could choose to assign a hotkey to a certain brush. I have almost the left half of my keyboard assigned to different brushes.
For someone who needs to frequently change his brushes, this feature is crucial to the speed of work, as the time takes to stop every few strokes to click on a menu adds up very quickly. Moreover, the action requires the movement of the cursor/pen, which breaks the flow of painting.
The right-click wheel can be used for some less frequently used brushes.

UI designers don't have to assign any hotkey to the brushes in factory settings. There are no concerns for reserving hotkeys for other functions. You just give the user the freedom to do so.

I dearly hope that this feature gets added in the future, and I don't think I'm asking too much either. Please! This is the only thing stopping me from making the switch to Krita and taking advantage of it's incredibly powerful features.

That's something we've been discussing a lot in the past, but we haven't found the right solution yet.