I already reported here the hot corner issue:
For that I made Bottom Overview - GNOME Shell Extensions which is a simplified version of Hot Edge - GNOME Shell Extensions. That’s the only rational way, I think, to use a mouse with GS. (Using a laptop, three fingers do perfectly the job.)
You mention some extensions that Ubuntu does maintain now (dock, tiling, desktop icons) and offer to all GS users. For sure, a native dock would be appreciated by some users, and I think it should not be a huge work (I did reuse GS dash to do that in Dock from Dash extension). But to be honest, I’m using only Bottom Overview, that respects GS design and has quite the advantages of a dock.