Source: https://www.youtube.com/watch?v=Vh1yKpzLdUs
Sure, the FX in many ways actually look better than they did in the 2015 example, they are short, but its not as if they couldn't do that now, the Idris explosion is very much like that example.
I think what CIG are doing is saving some of the more dramatic FX for the things you would expect, like the Idris.
This is not a case of something they demonstrated and aren't actually doing, they are.
Source: https://www.youtube.com/watch?v=HBFHuMkxz4A
Having said that, i really like the destruction sequence in that video, now given that in 3.19 due to persistence ships have two destruction states, one intact so they persist with cargo and components in place and the other in pieces with a lot of the cargo and components lost, for the Connie and its latter stage of total destruction i would like to see the example in the video cleaned up for the newer FX and brought in.