Yes it probably is complicated. I guess the problem is that even the new bts tickets require a tap for entry, but when you exit you need to insert the ticket, and it does not come back. And I am guessing (but I do not know for sure) that those gates don't support returning the ticket, because then a person having a bts only ticket would not get the ticket back, but someone purchasing a combined ticket would actually get it back, so it can be used again at the MRT.

But for sure, those new vending machines do show the whole map, not only BTS, but MRT, ARL and the purple line.