I remember using 8x8 midi interfaces to get around some of that - not just for the additional midi channels, but also to thin out the traffic for each connection. i.e. each midi channel would get it's own cable/connection.

However that approach didn't work when I wanted to send 16 channels to a single (non USB) multi instrument sound device like my trusty JV-1080. It became an excuse to buy more synths! :-)