We would clearly like to have visible passengers boarding and, there's nothing in the technology we use that prevents that.
However, we have some doubts about performances issues because, a human character can't be reduced too much in complexity, otherwise the skinned animations will not work very well so, having tents of humans moving together would surely impact performances quite a bit.
It's something we are looking into, though: we are well aware that visible passengers is one of the most wanted features.