The lesson which I saw after ETF rejected by SEC was, the private sectors maybe haven't seen that they can't get any benefit or profit into bitcoin that's why Etf has been denied. But this was only my opinion, regarding the results of the etf.
This would be the main thing on my mind too on which ETF have been rejected because government couldnt get a benefit from it since we do all know that bitcoin cant really be controlled or make money out of it or can be taxed.I dont know on what would be the other reasons but same as yours this is the thing that comes thru my mind regarding on the rejection.