I think you might be making one assumption though, in that moving the ADS into FSS freed up a slot. That makes smaller ships more viable as explorers and could easily have been part of FDev's thinking imo. Partly because more small ships will be explore ready multitaskers and also because the discovery focus has shifted a bit, on to planet surfaces. Extra slot means small / medium ships can take SRV more easily .. or repair limpets/ARU etc. and I wouldn't be surprised if FD see some value in that extra slot for new players in starter ships.
You have a point, except that FDev added slots in the next update, which they would have known was going to happen (we can presume).