I feel like this is largely a response to how quickly people stormed through Second Coil, with the i95 Leviathan weapons being a pretty big contributor to letting people further optimize at the i90 level to start taking them on within the first couple weeks. This time around, your only real viable options for Final Coil are going to be the Nexus, which is a gigantic time and gil sink that few people have completed, and High Allagan, which still drops from a fight that is almost certainly longer and more difficult than Shiva was ever going to be. If they don't want anyone but the absolute best of the best getting through T11-T12 in the first couple weeks, it's an understandable decision.

Having said that, yeah, it really, really sucks. This feels in a lot of ways like taking a step backward, not just from 2.3, but all the way back to 2.0, where the only viable weapon progression path was to get your relic, and then your Zenith. I felt that the 2.2 model was, on the whole, quite well designed, and it's a real disappointment to see this sort of regression in a progression patch.