It doesn't take you into the page like the redirect is supposed to. Also redirects can be pointed at specific parts of an article, bringing you right to the information, like Vedran Empire's section in they Systems Commonwealth page.
Just because you have the option to jump right to a page from the search box turned off doesn't mean that you can punish the the rest of us who do. You're not the only one who edits here. Despite what you may think you're not the sole authority. Imposing your will without even discussing it with the community is not the way to run a wiki.
Not from the articles itself. But there are plenty of people who can type for example, XMC, into the search bar, hit enter, and it takes them to the Glorious Heritage-class page. Because not everyone may know off the top of their head what an XMC or a DSX is. Likewise everyone may not know that Genite is a shorthand term for Knights of Genetic Purity.
Some redirects, misspellings do not need to be kept, but systematically deleting every redirect page is not the way.