You may have a correct implied point (which I also did think of before) which is that Gold ETF is allowed by the SEC because gold is effectively regulated (among other factors such as gold having a larger marketcap and historically perceived value that has been indistinguishable from its tangibility in the mind of most n00bs).
Well your statement is more clever than maybe you realize. We would like to perhaps assume that the properties of Bitcoin would not change if it were a currency, but I think we have shown in recent discussions in other threads, that if Bitcoin scales up to be a currency, then it will lose its immutability and thus no longer been an ideal commodity better than gold.
Indeed, which is why, when I think about it, for bitcoin to ever have an ETF, it must first have a very definite purpose of use (commodity or currency or settlement layer). Thereafter only can we draft the kind of regulation for it. Unless we finally make up our mind on bitcoin's
official use, its ETF will never come.
Because of this, I think for us to have a bitcoin ETF can be a very very long wait.