eBooks still need covers just as much as paper books do imo. When I browse an online store I scan covers, I know that isn't a fair way to judge the content of the book, but that's what I do
The cover plays an important part in whether I'll buy a book. After buying though, I like seeing covers when I browse my book library and decide what to read next.
I find it annoying when ebooks have a cover on the store yet the download comes with a dull "title" only generic cover. Thankfully calibre downloads new cover art easily enough that it's not really an issue.