For me the cost financially to buy modules and space required for a studio are really the only negatives. I do mostly weird experimental stuff that modular seems to excel at compared to traditional synths and I spend all day at work on a computer so the hands on tactile feel of patching cables to make sound is very attractive therapy. Plus I was not able to travel for vacations overseas for 2.5 years so the money I would have spent on vacations was funneled to modular instead. Love it! But now I have a lot of modules and no need to buy anything for a long time until I can master my gear and make tracks I enjoy.
-- sacguy71
I'm in the peculiar situation where I travelled a lot in the past, but I'm not anymore because I have a fairly young family. And I feel the disappearing money more in my shame about it than in my wallet. Which is good, because it makes me rethink every purchase 17 times so I don't make impulse purchases. It also gives me time to really get to know the new modules before I add even more.
Still, I've arrived at the point where space is becoming an issue. I wanted to start small but thanks to Jim's advice, I got an Intellijel 7U. It was a great idea at the time, so thanks again. And now it's nearly full. I usually take it down when my wife needs to use the studio to work from home. But if I should get a second 7U, I'd very much want to install it permanently somewhere, which means rethinking the room... again!
Another disadvantage is that the simplest things can become obsessive. Take patch cables. I have several varieties, which is OK. But I start fretting about how this one is way too flexible, and that one isn't flexible enough. These are way too long, but those are much too short to really route them well. The fit in this module isn't great, but the others don't really do it better. It's hell because there's incredible choice about everything. You ever looked at screws for your modules? Agh! Really! Who has this as a hobby anyway!?
Modular playlist on SoundCloud