There are lots of threads on kindleboards at the moment about book covers. It isn't surprising that people want to provide the best appearance for their writing as possible. I've also read some blog posts about the gap narrowing between indie and trad because of the higher quality of appearance on a lot of indie books. It is getting harder and harder to tell the difference between trad and indie published books because so much effort is put into appearance. It's always a good thing when indies are perceived to put as much work into their novels as publishing houses. When hiring an editor becomes known as standard practice for indies, it will be even easier for indies to sell.
I don't think I'm a particularly visual person. I'm a poor judge of covers. Book covers don't sway me one way or another. Neither do book trailers. Appearance is low on my list of priorities. But I can see the value of a good looking book cover. In any kind of business, appearance counts. Whether we like it or not, self publishing is a business so we need to treat it as such. I know quite well that I've gotten a couple of jobs based mostly on appearance, as sad as that may be. An ex-boss once shocked me by revealing he wouldn't have hired a man, an older woman or someone particularly ugly/fat/had a bad dress sense. Apply the same logic to an inanimate object and creating a suitable book cover becomes a little bit scary.
It's easy to feel so eager to upload your newest book that you skimp on the details. Maybe you don't edit it that one last time or maybe you take a short cut on the cover. Chances are, someone will notice the difference. But investing in a decent cover makes all the difference. For one, it doesn't make you stand out as a solitary writer who has self published their book. I am not one for hiding that fact but there is still so much stigma attached to it that I can see why many people want to choose to do so - if anything to persuade a reader to give them a chance in the first place.
For some reason, a well thought out and attractive cover gives a lot of people more confidence in you. Sometimes it makes them feel like the writer really cares about their work and therefore would be more likely to have the book professionally edited. It might not be true but appearances count for a lot. Someone who doesn't recognise your name is much more likely to read your description if your book cover is of a professional quality.
The world is quite shallow and appearances can always be deceptive. A good cover does not a good book make. But if a cover is a major factor in the buying process then it is a worthwhile venture investing a little time and even money into creating the best possible cover for your work. If you're serious and I mean serious about self publishing then shouldn't you expect to invest something more than five minutes into your brand? Your book cover often stands for you, it becomes recognisable along with your name. It is the first introduction to you and your work. At least do it some justice.
If you aren't sure on your book cover, just ask for my opinion. If I like it, it's sure to be a dud :)