The problem is not that caps lock is redundant. The problem is that it introduces a “mode”; the effects of your typing depends on past action, in a way that is easy to forget (and no, a little LED somewhere is not sufficient). This leads to mistakes and confusion, and adds cognitive overhead.
For an extended explanation of the problem of modes, including in keyboard commands, see Jef Raskin’s book The Humane Interface.
If you want to type an extended amount of text in uppercase, it would be better to, e.g., put “shift” on a thumb key (so that all other letters can be typed easily while holding it) or a foot switch, or something.
Or, what I do is just use a text editor with a keyboard shortcut for making text uppercase; so then just type a word / paragraph / whatever and then invoke the appropriate “uppercase” function after the fact.