This article establishes a novel interpretation of the readout current in ferroelectric tunnel junctions (FTJs), which we found to be rate-limited by trap-to-trap tunneling (T2T) in the ferroelectric (FE) layer. We show that, with a single set of material parameters, we can reproduce both transient P-V and quasi-static readout experiments for two variants of HZO-based FTJs featuring different tunneling dielectrics. Our investigation puts the simulation of the readout current of FTJs on a much sounder physical basis, which allowed us to then explore a few possible design options to obtain an increase in the readout currents and to improve the ratio between the on and the off currents. Our results suggest that the readout currents can be improved mainly by increasing the bulk trap density in the FE layer.