Actually, think about it a LOT more. Even back in the days when you'd only have a couple dozen modules from the manufacturer you'd opted to build a system from, getting that end-result right tended to take a lot of time, study, crumpled-up paper wads, hair-pulling, and confusing e.e.-type considerations that most musicians were ill-prepared for. Now, in the wild and wacky days of Eurorack, there's about 6,000 modules, it doesn't matter who made them because they all work together, and you have an unlimited choice of cabs from tiny to room-filling. Technically, that should make matters MORE confusing, but since you also have the awesomeness of a huge user-base, resources like MG here, and firms making stuff that's light-years improved from the bad ol' days of early analog, the confusion level seems about the same (if not a little less, actually). But there's no substitute for putting an initial version together, then whittling the hell out of it to come up with a well-optimized result!
Also, I really suggest looking closely at the great monosynths of history, and seeing why it is, exactly, that they're still coveted items. People crave things like ARP 2600s and Odysseys, Minimoogs, Pro-Ones and the like not merely for their sound; these synths also 'got it right'...their ergonomics, playability, rational layouts and so forth are a big part of why users still pay big bucks for them.
Take your time. Research things. The care you put into creating any instrument will reward you years on after you finally assemble it.