There's nothing exclusive about the two. Good systems should be self-justifying.
But if you want decent travel times the current BART can't provide them. You'd need something like Personal Rapid Transit to get good trip times at the intra-urban scale. But the same argument you are making here - envy of something that doesn't even exist - is why we keep getting the same transit systems that are hard to grow because they don't provide enough benefit to enough people.
But if you want decent travel times the current BART can't provide them. You'd need something like Personal Rapid Transit to get good trip times at the intra-urban scale. But the same argument you are making here - envy of something that doesn't even exist - is why we keep getting the same transit systems that are hard to grow because they don't provide enough benefit to enough people.