As you say Myron, the development of the basic geometry, in 4-D space (no extra dimensions necessary), has become more complete and rigorous. This has resulted in this extra insight into the subject. The inputs of Stephen and Horst have also introduced clarity (and confirmation) in their respective ways.
Dare I say it, but to be fair to the Standard Model elite, this deeper understanding was impossible in the absence of ECE theory. This is what important progress and the advancement of science is all about. The onus is now on the Standard Model elite to study their subject afresh and to appreciate for themselves the new richness and exciting possibilities that ECE theory, and Stephen's contributions, bring. Some ill conceived ideas, that are now unsupportable, need to be abandoned (Big Bang, Dark Matter, Black Holes etc) but they are replaced by concepts, such as Spin Connection Resonance, that seem to have important practical applications that could potentially change the very nature of the way we live (in ways that should be less environmentally harmful and more sustainable).