>Every computer comes with a browser.
There was a time when this was not true. No computers came with browser. Then the web got really, really popular. Browsers were added after the fact.
Even today, the share of non bundled web browsers matches that of bundled web browsers. http://en.wikipedia.org/wiki/Usage_share_of_Web_browsers
Bundling is nice. RSS should be bundled! But it's a red herring to say the lack of bundling, or the fact that it's got multiple vendors, is why RSS has not succeeded enough.
However, RSS has no default client. If you see a link that says "contact us via email" and you click it, your mail client responds to the mailto: link. There should absolutely be an rss:// (or whatever) protocol link that browsers can either handle internally or ship to whatever client.