Those two sentences don't match up. You can't assume a "base level of professionalism" with regards to "anything." Sure, there are plenty of good books out there, but there are also loads and loads of crap on Amazon (which Konrath should know as well as anyone, considering that he's read slush for contests, according to his blog). Some of that crap finds its way onto Amazon in an unedited and dreadful form.
Some people insist that every book can find its audience, and that one man's one-star book may be another man's five-star book. But I'm talking about books that are just bad, bad, bad. There are many excellent indie books, but there are also indie books out there that read as if they were written by a third-grader for whom English is a second language. These books deserve one-star ratings. They are atrocious, and should never have been uploaded to Amazon. They're an insult to the readers who spend money on them, and those readers are entirely justified in giving such books poor reviews.
To pretend that books like this deserve more than one star is to undermine indies who actually edit and proofread and craft their books.