I see the main problem in that we do not have any standard (I mean dimensions of the cards).
The factory solution allowed to connect just one expansion card.
As far as I know, the bus for more cards was not factory solution.
Now, appeared possibility of use the cards available for CPC and MSX.
Question: Should we adapt to devices prepared for other platforms that are not quite compatible with EP (not only dimensionally), or create our own standard of cards ? (witch matching physical dimensions to currently available casings)
At the same time, we should consider how many cards we want to connect at the same time, so not to bring the situation as, for example, in the ZX Spectrum, where a tiny computer trail a long train of cards.
Currently, we have more technological possibilities than past and, in my opinion, building new devices according to the old formats and sizes of cards that hang behind the computer without housing, is at least inelegant.