Iow something that clutters up the user space and far from not needing to be sorted actually being uncustomisable and of limited use.

Well, space shouldn't be a problem nowadays as computers usually come with lots of space.
Anyway, it doesn't need to index all the pages, it could index only the pages that the user wants.
Another alternative would be the use of a(n) (automatic) tag system.

Harddrives come with lots of storage space. Screens don't come with lots of viewing space. You know I wasn't referring to the former. How is it going to index only the pages the user wants? Oh yes! BOOKMARKS!

ranted there may be the occasional email only user or the person only using their browser once a month but even most of the non power users have found bookmarks to be helpful at some point. There's no denying that for those who need and use them they DO work.

As i said, it may work for some but it doesn't work for others. It's 50/50.
On a classic bookmark system the person needs to decide if that page should be bookmarked or not then choose where to bookmark it - depending on how the person sort their bookmarks, a page can be bookmarked on various (sub)folders. After or while doing it, the person changes the bookmark/page title to makes it easier to be find.
Too much work for me. I would like to be able to type something on the address bar and get a list of pages in which those words appears, including a "preview" of the text. Like in Opera Presto.

You know it's not 50/50. Come on be honest for once. So bookmarks is too much work for you but you can't assume the majority don't use them when they in fact do. Again what better system do you have that provides all the functions? An index only works if it's still cached. And it doesn't solve the problem of being no better than google in pointing out the correct page but instead a load of irrelevant garbage.

Google or any search engine for that matter can never be a replacement for bookmarks.

Maybe but people nowadays use them more and more to go to pages and to find (already viewed) pages. People search even for urls they already know.

Not an argument for replacing bookmarks.

And what if the page is one of perhaps 80+ very similar pages that each carries a different weather-satellite image but has no uniquely searchable page text?

Well, maybe a manual tag system.

Which we then call bookmarks. A hundred internets to you for reinventing the wheel just out of stubborness not to remove it.