Yes, you both make good points. It wasn't much later that the grim horrors of WWI took place, but I still admire opening up the concept of nations meeting all at the same time, rather than following only the traditional path of embassies/ambassadors, etc. And you are right, if I understood correctly, about the successors to the Revolution in Russia partnering with oppressive regimes.
I have read that the mustard gas was horrific when one's exposure was severe enough; pain from burned skin, throat, and sometimes a very slow death. But you are right that modern technology has intensified the lethal effects of chemical weapons.
Yes, you are also right that there is no direct connection between Nicholas and the League of Nations or the UN. But I believe that the creation of the Hague was an important statement on the value of speaking out conflicts and creating codes of warfare between nations, some of which we finally began to respect (like the treatment of prisoners.)
The Hague also has a personal connection for me and for Russia. When we adopted our 2 Russian boys, we had to comply with laws created in a Hague convention; those laws were designed to protect the kids. On our end, we had to submit regular reports regarding the boys' progress, attachment and general welfare. And this is what diplomacy does well, connecting citizens of different countries into a system to promote peace and fair behavior.