Per my understanding KYC do have both pros and cons in its own manner. KYC is basically required for AML i.e. Anti Money Laundering. so that bad investors cant simply put the black money directly in ICOs. Every project has the right to understand and make sure that the money that is being invested in there project is legal.
Over the cons, if the Project or Team is scam and use the KYC details to sell further on, its really bad for investors on there identity theft.