Then Google realized you could combine the two; this makes it less likely you will use a competing search, gives you more places to show ads (as more things qualify as search) and most importantly - legitimizes tracking every page you open - as you did a web search for the URL!
Unfortunately, Chrome owns the web, and Mozilla copies everything they do. Especially when they are FF's main source of income.
IMO, the old system was more accurate and more private. The search bar is for web searches.