First, let me begin by making the distinction between writing for the Internet, and writing period. When it comes to writing for a magazine, a newspaper, or writing that epic novel, you are essentially writing for an audience. When it comes to writing on the Internet, you are essentially writing content that is intended to get recognized in a search, and connect a buyer and a seller. In fact, based on what I have found, writing on the Internet for a number of years, is that most of the material you wind up working so hard to get right doesn't even get read at all.
But, getting connected in a search, and more importantly making that connection with a buyer and a seller which is the bread and butter of writing on the Internet does require some ability to write. That is because in order to make these connections, and in order to constantly make new connections, you have to be able to to write a lot of content.
In a recent hub I wrote, Content Is King of the Internet, I referred to this as volume of content.
If you can't write well, and more importantly, if you do not have the ability to create like content without simply regurgitating the same stuff, you will not do well. You need to be able to say the same thing 10 different ways in order to be able to generate a ton of content. That takes some writing ability.
I used to slam those guys who were all too focused on SEO and keywords, but lately as I have found that the key to making money on the Internet has nothing to do with writing, but rather what you are writing, I have changed my mind a bit on this. The best revenues from writing on the Internet that I have enjoyed have been from simply creating content, and targeting that content as it applies to what is trending in searches. This affords me frequent payouts from Google Adsense, for example, but does not require me to be the next Stephen King, or write the next grand Time article—although either of those things would be nice for obvious reasons.
If you want to make money writing on the Internet, simply write. Keep writing. Write about everything and about nothing at all. Just create content. Create a ton of content. And keep looking for ways to create more. Eventually what you write will wind up in a search engine somewhere, and hopefully what will find their way to what you write will not be a reader. But rather someone who is looking for something to buy, which means, so long as they click on an ad, who cares if they read a single word of what you worked so hard to write. The payday comes from the ad that was clicked on, not necessarily the words on the page, even if the words on the page are what ultimately led them to the page in the first place.
Make content your focus, as was more deeply covered in Content Is King of the Internet, and making money writing on the Internet will be as easy as making apple pie.