The ECHR is very obviously writing brand new legislation here, completely outside of the democratic process. The argument of “well that’s good because I think the democratic process should have already created this legislation” is simply anti-democratic.
The ECHR rules that Switzerland has failed to meet its treaty obligations WRT climate action. IE, there's been an internal failure by Switzerland's government and courts to enforce its own legislation and treaty obligations. So, these women took the next step - an international court (to which Switzerland is a party - if the Swiss don't like it, they should vote to abandon their obligation to the ECHR).