Currently the only way to add games to the download queue is by installing multiple at the same time, or by pausing an ongoing download, neither of which are ideal, because sometimes downloads have already started, so the options are either to wait for it to finish before you install something else, or pausing the download to install another game. The former is inconvenient because many people are just letting something install while they go do something else, and the ladder can sometimes cause file corruption, and is also pretty annoying to do.
I think adding a new option on games to add it to the install queue instead of installing it immediately would be very convenient and useful and good and stuff.