Only cryptographers care about &quot;unpredictability.&quot; Outside of cryptography, the interesting properties of a PRNG are speed, period length, and state size.<p>But a good CSPRNG has excellent statistical properties. So if you make &quot;unpredictability&quot; a requirement, their slow PRNG becomes very attractive. In other words, they made up a problem for their solution.<p>If you need a statistical PRNG, use a statistical PRNG. (The best are xorshift1024* and xorshift128+.) If you need a CSPRNG, use a CSPRNG.