I wouldn’t call it “necessary”
BUT …
Modular synths are the most versatile electronic instruments I know. We can either buy a pre-configured system or configure one by ourself. How the sound is created and how it’s shaped and modulated is totally up to us. There are so many individual ways and so many options today to set-up and use modular synths that it takes some time to sit down and to develop an idea, where to go. It’s freedom pure. We can go East-Coast, go West-Coast, combine both, we can use analogue circuitry and combine it with modules having digital technology at their core … and … and … and …
One thing you might know already … this freedom has it’s price. As an example, there are no “factory-presets”, at least not in the sense, we are used from most “keyboard” or “desktop” synths. We have to program the synth by wiring our way through the modules, which are supposed to create the sound and the support for our performance. Some knowledge or good advice about how to configure a modular synth is important too, to get a cohesive instrument and not only a loose collection of interesting modules.
Well … and have some money in your pocket to spend. The single module might not seem to be too expensive, but at the end of the day there are some modules needed to built a decent synth and there are so many interesting modules, which cry out to be checked …
One thing guaranteed … much fun, a live-time full of creative inspiration, sound, and music … and sometimes other people wondering about you, what you are doing, and what the heck this mess of all those wires, and knobs, and lights is supposed to do, and how you can manage all this chaos