Original poster here:
So happy to see a new browser that will solve the problem: Vivaldi! Still in development is supposed to pick up where Opera 12 left off. Its already amazing!

And the bookmarks bar isn't a suitable replacement because?

Not a replacement because:
I have 30+ folders of bookmarks, each has 10 or more bookmarks, some are in subfolders. There is no way a single line of horizontal bookmarks is going to work.

Yes, I can manually move all my bookmarks from firefox to a single folder in the horizontal bookmarks bar but import does not work there.

Furthermore, web sites are narrow, my screen is 20 inches wide, why would I want to use part of the narrower vertical space when the unused width is there, ready for a side bar.

I am not asking to replace any other bookmarks system, just return the optional basic, simple, functional sidebar.

I didnt know OPera was a re-skinned chrome browser, no wonder it looks exactly like google chrome.

I just tried Opera for the first time in 10 years and the bookmarks are impossible to use. I have been using firefox since it was called foxfire, and always have a vertical panel on the left with all my bookmarks open. It is a simple way to access the hundreds of pages I visit periodically. The folders have sub folders and are very easy to see and click through.

I tried to access the imported bookmarks on Opera and they came up in huge buttons that required a lot of scrolling to find them 15 pages down. I could click the list view but each sub folder of each folder is in giant icon view requiring that I click list view each time. Operas bookmarks bar does not appear to make use of the imported bookmarks and only allows for one horizontal row of bookmarks requiring folders to be opened each time you click on a single bookmark. I find this tedious.

With Firefox, its a simple activity, I can click a link without leaving the page I am on, and middle click the mouse to open in a new tab or open multiple pages in a folder all at once. If I want a clean display I can just close the bookmarks sidebar and its gone. Mozilla is messing with the user interface making this harder to do, but it is easy enough to customize the browser and fix that.

I am using a desktop computer, Opera, like Chrome seems designed solely for a tablet user so I will have to go back to Firefox for now. If Opera had this basic 1990's functionality, I would love to use it.

My request would be to add the basic functionality of a sidebar for bookmarks.