France and Russia had been allied since 1894. After slowly inching together diplomatically, chiefly due to their shared insecurity about Germany, they signed a formal treaty in this year. The treaty was popular with France, who had previously been relatively isolated among Great Powers, and was also quite popular in Russia - although Russia had a substantial pro-German lobby and a tradition of alliances with Prussia, the state that Germany was a quasi-successor to, many Russian opinion leaders had become suspicious of Germany for a number of reasons, chiefly because of Germany's status as protector of Austria-Hungary, whose Slavic territories they coveted, but also due to their fear that Germany was planning to annex Russia's Baltic territories, which were dominated by German-speaking nobility who still had ties to Germany proper. The French alliance was a particularly cherished project of what we might somewhat anachronistically call the pan-Slav 'lobby' in Russia, who sought to liberate the Slavic minorities in the Austro-Hungarian and Ottoman Empires, and who saw Germany as the main obstacle to this. France's need for an ally against Germany had a simpler explanation in that Germany's annexation of Alsace-Lorraine was still viewed as an illegal annexation in France, and rising nationalist sentiment demanded a return of the two provinces - something that was only realistically possible if Germany was defeated in a war.

So the Franco-Russian alliance didn't just exist, it was formed around the two country's shared enmity with Germany. At the time the Moscow-Paris alliance was seen as a success, and it certainly did make things more difficult for Germany - it also preceded the Anglo-French alliance. But without it, as you've pointed out, World War I would have likely been much shorter and less bloody - although it would also, without Anglo-French involvement, have likely resulted in a pretty swift Austro-German victory.

Source: Roger Magraw, France: The Bourgeois Years, 1815-1914