I researched this topic a little bit so I can share my findings. There are a few factors in effect.
First of all - the new tyres model. It is an estimated 20% lower grip than previous games. That said, the tyre contact model is more complex (increase from 4 to 12 points IIRC) leading to theoretically more progressive grip.
That said, TC mechanic is supposedly not adjusted to this loss of grip and hence works much less effeciently.
Another factor is that the game got released without the intended torque transfer model that should decrease the likelihood of spinning significantly. What I understand it will do is soften the torque transfer from engine to wheels, especially on lower gears. The wheels will be driven with more strength but less speed, if that makes sense. The intended model is coming supposedly in one of upcoming patches.