Yes. I read a lot of series contemporaries. Short, easy, and kinda mind numbing. I see as lot of repeated pronouns in those reads.This doesn't sound like something exclusive to e-books. It's generally much better to vary sentence structure. If every sentence in a paragraph starts with the same, or similar, pronoun, the writing becomes sing-song and boring. By varying how you start sentences, the text becomes more exciting. This is true whether you're writing suspense, romance, or a very dry statistical study. And thank God I don't edit that!
I'm surprised you're finding it that much in print books. I read voraciously, print and e-books, and can't say that I've come across that as a general trend. Maybe you've been reading poorly edited books? Either the author or the editor should have noticed and changed the sentence structure on re-write.
And there's always the possibility that the similar words would line up under each other, making the page look, well, weird. Though e-book editors don't usually get to see how words line up in the final e-book.
Does this answer your question?