[DenisM]

I think most people wouldn’t mind writing a thoughtful letter if they knew that the recruiter will put thought into reading it. However most applications are discarded before that, which means one has to apply a lot to get a chance at hitting someone who will actually give you a chance by reading what you wrote. That in turn makes it impossible to put effort into every single one of them.

Have some compassion. Maybe try applying for jobs yourself and see how it looks from the other side.