Supersized rocky planets are out there.

[Anomalocaris]

If Kepler found fewer than expected there are two possible reasons:
A) Kepler's design was flawed.
B) Our models of the dynamics of solar system formation are wrong.

I have no doubt b) is true to a certain extent. Our sample size and corpus of data is too small. They are at least incomplete, and I doubt there many planetary scientists who think otherwise.

I'm not privy to what was expected - so won't comment on a) or whether additional possibilities exist.

It's not that our model of the dynamics of solar system formation are wrong. It's our model is supersensitive to initial as well as boundary conditions, and it is extremely difficult to solve. So to get anywhere near a solution that resemble our own solar system - the only one we knew until early 1990s - we used many simplifying assumptions.

But once we got rid of those assumptions of convenience, we found our model of solar system formation could lead to much wider range of outcomes than we imagined, and our solar system with orderly arrangement of small rocky planets inside, large gaseous plants in the middle, and moderate sized ice giants on the outside in fact seem to represent a very unlikely outcome. In most cases, the orbits of gas giants swing all over the place, often ending up near to or colliding with the parent star, but in the process clear the planetary system of any incipient small mass rocky planets.