I am definitely not an expert in this. For SMT the size of the pads (and more accurate the size of the holes in the stencil) directly influence the amount of solder paste, and therefore the solderability of the components.
THT components in automated processes are usually done with wave soldering. For your connector, the tips of the pins get dipped into solder, and capillary forces such the solder into the hole. You can even get away with very small annular rings on the pads.
For handsoldering sometimes larger pads are made, see for example the “longpads” examples in KiCad’s libraries. Pads for handsoldering are big, because you want to heat the pad with your soldering iron on one side, and apply solder to the other side of the pin. If you apply solder directly to the soldering iron, the flux will burn off before it can do it’s job of cleaning the pad (which is a mistake beginners often make).
The amount I made the pads narrower is almost certainly negligible. The change to the pads is only from 1.4mm, to 1.25mm. which is about 10% Adding those 0.15mm to the track width almost doubles the room available for the tracks.