Although they don't have memory you can always leave a pre-determined signal patch patched, then program as you would on any other analogue without memory slots. Once you get tired of that signal path, try something completely different.
Having said that though, this pic bellow would have so many patch possibilities, that I wouldn't know where to start.
There are always synths like the MS-20 which have a hardwired signal path until you plug patch cables in. Having true analogue modulars can let mix and match machines too.
I think if I were going for a modular I would go for a small one though. Maybe a system 100 set. Anything too big would be too much work.
I have an Analogue mono (not modular) and having no memory slots isn't a problem at all. Programming it is so damn easy and because most mono synths have their speciality (bass for example), then you are using them for one style of sound.