I dont have much to add that you haven’t already mentioned, but YES, sketching is important.
The only distinction I would make is sketching vs. rendering, which I feel is less important. A good sketch communicates a concept, idea, direction, thought, etc. It doesnt need to be fancy, doesn’t need to necessarily be 100% correct (proportion/perspective, etc.), but it should get across as much information with the minimum of time/lines/effort.
IMHO, a good sketch should be disposable and not a work of art. It’s purpose is communication of an idea and its role in the design process is one that is temporary.
I’ve ranted about this before, but i’ll mention it again as i think it’s relevant (and billymenut touched on it)- all too often I see designers consider a sketch/render precious. Spend 8 hours on a PS rendering, when there is no additional info that a 5 min sketch wouldnt communicate. This is backwards. Renderings have their time and place, but i consider a sketch like a snippet of verbal dialog. You wouldn’t spend hours carefully crafting and proofing a formal speech about your concept in the middle of a brainstorming session… a sketch is a visual equivalent of a conversation exchange. Get your point across as simply and easily as possible, generate feedback, adjust direction and move on.
Nicely worded reply, btw, Yo.
R