I found five reasons to write in conventional POV, at least until you already have a large and loyal readership that will buy whatever you write just because your name is there on the cover: confusion, distraction, expectation, experience, and reputation.
Confusion: If the writer hasn't made it completely clear who is talking/thinking/important on a page (more difficult than it sounds) then the reader misses information. You want to make every word count, right? If your reader is missing information because she can't figure out who's talking, your carefully hoarded words are not working!
Distraction: If your reader is confused, she has to go back, re-read, figure out, read again...in short, she's been pulled out of the story.She might say to herself...Hmm, I'm hungry. Oh, the dog needs to be let out. Dinner's ready! Bedtime already? No, I don't want to read that book anymore, it was confusing. What else can I read? And you've lost her. UGH!
Expectation: When a reader spends his money on a (insert genre here) book, he has certain expectations about the way that story will be told.Will he be happy reading a murder mystery in which three of every five pages is about battling space monsters? Probably not.Will she be expecting seven main characters in her romance book? No to that, too. Just as a reader expects a story to follow certain plot conventions, readers' expectations include familiar point of view. Without that familiarity, you might be right back at "Distraction."
Experience: Point of view affects a reader's response to the characters of a story. In murder mystery, knowing everything the narrator knows is not going to make things mysterious! In an action story, the reader will not feel the rush of jumping out of a plane if the writer is talking about how hot and sexy the hero is from the pilot's point of view. In a romance, the most important thoughts and feelings are those of the hero and heroine, not the tow-truck driver or the cabbie, unless those are the hero and heroine.
Who is the reader experiencing? Whoever the writer has written, of course. If that experience is not what the reader expected, again, you are back to distraction.
Reputation: Most of us write to sell, even if we first write for other reasons.When a reader buys your book, Whooo, baby, that rocks! But if the reader couldn't see how great the story was because it was also confusing and distracting, you've lost the next sale. Besides that, your reputation is damaged, and word gets around, so you've lost other sales, too.
OK, here's the cleverness:
Don't let confusion distract your reader and ruin her experience. Meet his expectations and your reputation will be on the rise rather than at the bottom of the ravine.
I found some highly useful information about how, how not, and why to accomplish tight, clean, appropriate POV here, here, here, here, and here. I actually found a surprisingly large number of blog posts about this topic. If you're interested, I'm sure you can find them too, so I won't list them all here.
What is your favorite POV to read? To write? Why?