The Problem of "Worthy Content"

Has anyone managed to get around this problem of "worthy content"

You always here people talking about how long term rankings are achieved by having a worthy website with really good content that people will want to link to.

The fact of the matter is, most websites on the internet aren't Facebooks, or Amazons, or the IMDB or gawker type blogs and don't really have anything worthy to talk about

Most just have some random product they are selling, whether that be article writing, casinos, cosmetics, viagra, merchant cash advances...whatever.

Is it worthwhile to invest in content writing then for your site? I mean, I see some really basic sites that have maybe 20 pages and they manage to outrank sites with thousands of pages for keywords.

Also, I noticed that when I am consistently updating my content, google cache's my pages more often - does this help in any way for SEO?

It just depends on what you want - and you should act according to your target.
If you want to have a super authority site that will give you natural backlinks, invest the time/money to create great content.
If you want to sell a product, get on the first page with any weapon you can think of. Great content is just one gun in your arsenal

In an ideal world, Google would want the site owners to write their content themselves. As long as their algorithm feels it is being done that way - and updated constantly, that site will rank well. There could be a monster site in the same niche which has a truckload of paid content coming in, and it'll have to deal with all the craziness Google is associated with. The small site will do just fine!
But since that is not really possible after a level, we just try to keep content semantically similar and update it often (without going overboard). The problem of plenty arises after a while, but I guess each of us has our own solution for it