I personally think the design (size) is more influenced by trying to achieve domestic tranquility ("you're not going to put a big ugly box in my living room"). They used to call it the WAF before we all became sensitive caring life partners.
The most import design issue for a speaker manufacter how many will fit on a pallet.
You may disagree but with standard imported designs is a major design issue and it's factored into what you are most likely using now. Its also not discussed by audiophiles but it affects performance in a major way. I understand manufacturers need to make profits or they cant make products. But do keep in mind when you look at that bookshelf its design isn't just about sound its about profit shipping storing packing as much as the sound.