There are a lot of people that prefer their bookmarks to ALWAYS open in a new tab without pressing ctrl (cmd) + shift + left click, me being one of them.
This is already implemented in Vivaldi, so it isn’t an issue with chromium. So nothing stopping Brave from doing this and loads of people are asking for it so why not?
In fact a solution that Brave can implement is make Brave think that control and shift or command and shift for mac are down when your cursor is above the bookmark bar, which is how Vivaldi does it.
Only thing is that this or some other thing that does the same job needs to be implemented.