I didn't actually know that. The difference between B5 and Crusade is like day and light to me, but I've never picked up on changes during the original series' run.
Yeah, I followed it closely at the time and it was all Star Trek's and JMS's fault. To me a big part of Babylon 5 was due to the great ships and effects done by the Foundation Imaging effects company founded by Rob Thornton. Even now nothing comes close to their ship designs which actually show off how advanced a race is and what kind of psychology they favor. Like functional gray EA ships compared to colorful Narn ships or elegant Minbari ships, not to speak of the living ships of the Vorlons and Shadows which was an idea of Thornton which JMS just worked with.
At that time Paramount had already used the first draft of the Babylon 5 script, pitched to them earlier and rejected, to create DS9 which angered JMS a lot, rightfully so in my opinion, but they still used models in their effects. After seing what FI was doing for B5 they decided to buy them off. Thornton wanted to do effects for both shows but JMS was angry again and feared to get less attention from FI compared to ST so he let them go and with the producer of B5, Douglas Netter, they founded Netter Digital thinking they could just reproduce the stuff FI made. They couldn't!
The switch was done in the middle of season 4 which can already be seen in the Drakh ship design. It got worse in season 5, Crusade and everything after that because they just didn't keep the standards of FI to keep the effects as consistent as the rest of the show. Speaking of which, have some of you tested my Star Fury Pilot patch yet? Because I improved it some more to bring some of the missions closer to the way they were shown in the original series. Only in minor ways like the Narn cruisers in Twilight Struggle not attacking in line. Should I upload version 1.1 somewhere?