Why? The country was developing and without a war you wouldn't have the economic, social, or political upheaval for a Revolution.
Precisely
because the country was developing; it was the growth of a bourgeoisie in Russia that led to instability, this new educated and skilled class leading the demand for change and an end to the autocracy. It was those demands, principally for political reform, that boiled over in 1905, resulting in the beginnings of revolution. The Tsar, in an effort to save the dynasty, was persuaded by Witte to issue the October Manifesto, guaranteeing universal male suffrage and a legislative parliament, the State Duma, civil freedoms including an end to censorship and freedom of religious belief, and legal reforms including peasant access to the civil courts.
Had Nicholas II honoured the manifesto and permitted reform, then Russia probably would have evolved reasonably peacefully into a parliamentary democracy; that was after all the ambition of all of the leading political parties, the Kadets, the Socialist Revolutionaries and the Mensheviks, as well as the Octoberists. However, no sooner had Nicholas released the manifesto then started backpedalling, claiming that the October Manifesto placed restrictions on the bureaucracy, not on him as autocrat. Witte’s replacement Stolypin found the Duma impossible to work with and advised the Tsar to dissolve it and pass bills by decree, winding back the voting franchise until the Duma was dominated by the aristocracy and wealthy landowners. So having raised expectations of liberal political reform, Nicholas shattered them, undermining the liberal political parties in the process.
Stolypin, in an effort to strengthen loyalty to the state amongst the peasants, tried to introduce land reforms and a widening of land owning peasant involvement in the zemstvos, the local district councils; through these reforms Stolypin hoped to create a yeoman class, whose new stake in Russia’s prosperity would guarantee their loyalty. But his reforms were blocked, by the Crown, by the landed aristocracy, and, ironically enough, by the very peasants he was trying to empower, who overwhelmingly rejected the proposed changes, preferring the unchanging poverty of the village commune to the new ideas from outside the village.
In the cities the legislated industrial reforms, banning women and children from working at night and reducing the working day from thirteen hours down to eight, were ignored by factory managers with impunity; the government did nothing to enforce the new laws and the police aided strike breakers.
All of this resulted in a steady build-up of anger, with terrorist actions by the SR, Mensheviks and Bolsheviks, and a steady increase in industrial action and worker militancy to the point where, in the first half of 1914, more than half the workforce had been on strike and workers seizing factories was a common occurrence. Sans war in 1914 things would have continued to degrade, since public anger was continuing to grow and Nicholas was determined to prevent any encroachment on his autocracy; the Black Hundreds, armed bands loyal to the government, along with the army, were regularly being used to breakup strikes, attack socialist political rallies and launch pogroms against the Jews, and it is hard to see how all of this unrest could have continued much beyond 1920 without a revolution.