It isn't an "extremely careful" type of situation. It's a "take 50mg first and be aware that skin outbreaks can be caused by modafinil" type of situation.
This isn't well understood because there are so few cases, but it's believed to be effectively an allergic/histamine response, and I've never heard of a case of it developing after regular use (sensitization), only initial exposure.
In terms of how often modafinil causes Stevens-Johnson Syndrome (or whatever actually happens here) it seems to be about like aspirin and Reyes syndrome, but without susceptibility being limited to the very young.
A pill is 200mg and that's a lot of molecule (I find it a high dose as well, ymmv). Everyone has to find their own risk threshold, but "take a quarter pill at first just in case you're the 1/100,000 who gets a rash" is my safe bet for risk mitigation.
For context, my first -afinil was adrafinil, which I imported from France around 2000 on the strength of some blog about how it was a preferred treatment for ADD (the H wasn't a thing yet) there. Adrafinil metabolizes to modafinil, and France is a pretty big place with a unified modern healthcare system, if this adverse effect were more than very uncommon I figure it would have shown up strongly enough to have prevented that in the first place.
Apparently the skin issues from it can be so severe it’s being warned that Stevens-Johnson Syndrome is a possible adverse effect of it.
Initially first results showed that despite the warning there had yet to be an actual case in documented literature, but scrolling further showed a case in an early 20’s patient in 2018. Scrolled back up, & the first results were from 2017… so yeah I guess.