Sure, putting them for the looks (e.g. putting a huge clock widget when your lock screen and status bar already show that info) might be useless and redundant, as you say.
But other widgets (e.g.quick notes, schedule widgets, maybe even a news widget that syncs once a day) are perfectly understandable, especially for some home configurations that prefer simplicity.
As an example, I'll give my home screen: it consists of three pages, one of them is empty, the other two contain three widgets: notes, schedule and news (syncs once a day automatically). The dock contains 5 items, each of them has one or two gestures assigned. The dock's middle icon opens the app drawer, divided into several tabs.
In order to open each of these widgets' apps' screens that interest me, it would take me between two and four clicks and one or two swipes to get there.
Considering I use them regularly (the notes and schedule widgets, a few times times a day [3-5 each] and the news widget, once or twice), it would be way faster and more efficient to have the widgets instead of removing them or replacing them with icons (should I do that, it will still take me one to three clicks to get where I want, plus the loading time).
Plus what Tomaxda said about widgets.
Also, I'd suggest adding Tasker to your list of apps. It's not for the lazy people, but I can get it to do all of what the apps you listed do.
Sorry for the block of text. Great guide.