Why would you apply to a company you didn't know well enough to want to work at? You should have some reason you're applying to the company. Think about it this way: if you're already an employee of the company and someone applies who doesn't really want to work there, and HR lets them through, would you want to work with them? I wouldn't.
But even if you can't write a good "I want to work and Foobar Inc." paragraph, the cover letter gives you a chance to talk about all the stuff you do on the side, to show how much you love making software.
Personally, I would much rather work for a company that hires people who love working there than one that hires people just because they know a guy who knows a guy.
1) I'm looking to change locations, half way across the USA
2) I've been in my current position for nearly five years, and am ready for a change:
2a) In my chosen trade (being a unix sysadmin) you often get tremendous latitude in selecting tech, tools, and tasks, but cross pollinating with the technology stack at other companies gives you answers to questions you didn't even know you had and makes you a better employee for it.
2b) I'm a disbeliever in the "you've got to get out by the time you're forty" age discrimination stuff. I have, however, seen a lot of people, both young and old, that have spent long enough in one industry that they were not hireable for a position in mine because they'd spent so long in a single frame of mind that they fell flat on their face after several attempts to coax them through design/architecture questions.
Think about it this way: if you're already an employee of the company and someone applies who doesn't really want to work there, and HR lets them through, would you want to work with them? I wouldn't.
Sure, if someone actively doesn't want the position they applied for they should have told the recruiter "thanks but no thanks", but, frankly, if I find a job I'm interested in, the interview is mutual: while you're determining if I can reboot routers with style and grace, I'm determining if you're a sweat shop, if my potential teammates are idiots, and if my future boss is a jerk. In my opinion it's the employer's job to sell me on why I want to work in that industry, rather than the other way around.
Ever tried dropping your age from your resume? There is no requirement to put it on. If you get into the interview and the interviewer has an, "Oh, you're not what we're after" moment you know why. In this country that is grounds alone to sue so most companies will give you a decent interview, at the very least.
The approximate age of the candidate is going to be glaringly obvious even without a date of birth. It's easy to infer that they're over 40 from things like graduating college in 1975, having 20 years work experience, etc.
Actually I'm currently in the prime of my hiring age, and it's not listed at all, but it's very easy to infer, particularly if an individual has dated their college history (I honestly don't recall if I did or not).
I don't know why you're being downmodded for that comment. You're quite right about people just applying to anything and anywhere without a forethought or research.
It happens all the time. People apply for jobs because they need the money, full stop. If that's the kind of shop it is, then the hiring manager should just embrace it.
You get a job because you want to make money. Whether you write Java stuff for bigcorp a or bigcorp b doesn't matter, they are going to require the same skills so they are "commodity" work places. You get a job there because you love to code and would like to make money. In short, you love to work.
Now, there are a few exceptions, of course, such as Frog Creek or your dream job, where you get a job because you love to work there.
Using this as the policy at your company does mean that you probably need to be marketing your company as a great place to work. If no one knows why your company would be a great place to work, it's a bit unfair to expect them to write about why they want to work there and be honest.
But even if you can't write a good "I want to work and Foobar Inc." paragraph, the cover letter gives you a chance to talk about all the stuff you do on the side, to show how much you love making software.
Personally, I would much rather work for a company that hires people who love working there than one that hires people just because they know a guy who knows a guy.