Companies can either care about cover letters, or not. Applicants can etiher write genuine, informative letters or generic useless letters.
There are only two possible stable equilibria: a "low" don't care/generic letters or a "high" care / informative letters. If most applicants write generic letters, there's no point for the company to pay attention to it. If companies don't pay much attention to it, there's no point in wrtiting more than the blandest, lowest effort letter.
Sounds like you're in a field in the "high" equilibrium. Most of the software industry is in the "low" equilibrium.
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Personally I like cover letters (in the "high" equilibrium of course):
- they basically front load a lot of the interviews, with information that come up in the interviews. I'd rather have as much filtering as possible thourgh the cover letter and CV than in interviews, because it is much more costly for both parties to interview.
- people complain that it overlaps with the content of the CV/resume. The question imho is purely one of presentation: do you want to convey information with full sentences and paragraphs or bullet points? Much like I think powerpoint-style bullet point lists are much worse than actual language to convey rich information, I'd rather have actual text than blurbs in the typical resume. Makes it slower to read and thus requite low number of applicants though.