When I was (a lot) younger, I used to do music radio shows. The tapes are now safely locked away. If you’ve never done it, I can assure you that chatting away to a foam-covered microphone can be every bit as awkward as you might imagine. Some people never work out how to make it sound natural.
Of those who do get over the hurdle, many (including those with unnaturally big egos) do it by imagining all their audience in front of them. Those like me, who would find that rather too daunting, picture just one person there, and talk to that person. (I suspect that this, by the way, is why radio shows with two presenters often sound so much more natural).
I point this out because it’s the same with writing marketing material (and lots more writing besides). If you just write without thinking, it can be a bit stilted. It’s how we get so much marketing copy which appears to have been written by robots, with words like “solutions” which nobody would use in normal conversation.
However, if you write with all of your customers in mind simultaneously, you can produce copy which sounds a bit messianic. Seriously, it’s only a blue widget. The best approach is to imagine a single customer in front of you and write for them. Indeed, why not write this imaginary customer a sales letter and see what comes out of it?