> This need for a cover letter is essentially asking candidates to tell you how much they love the company and how much they want the job.
No, and that is exactly the wrong sort of cover letter. A cover letter is a letter from the human applicant to the human hiring manager explaining why he feels that he is a good fit for the position. ‘But that’s the resumé!’ you might say. No, a resume is a list of relevant training, skills and previous employment. Although not traditionally machine-readable, a resumé is basically input into a process machine (we want someone who has been programming in Java for twenty years; this candidate has done it for 24; awesome). The cover letter is input to humans.
Humans whom you will potentially be working with, potentially for years. It seems reasonable for them to get an idea of your communication skills and empathy. Exercise that empathy: put your self in their shoes, and imagine what it is like to receive hundreds of resumés. What would you want to receive from a candidate? What would make your hiring decision easier or harder? Having figured that out, communicate it.
> As a job applicant I’m not going to invest a minute in your company until you’ve read my resume and expressed an interest.
It’s a free world. You don’t owe hiring companies anything. Of course, they don’t owe you anything, either. In a booming hiring market, you may find that you can easily find positions without investing in leads; in a softer market, you may find less success.