you are equating negotiation and appeasment with eachother, They are two very different things,
Negotiation is TWO equal partys BOTH making compromises to find COMMON ground
Appeasment is ONE party making demands, and another party submitting to all demands, as made.
WW2 was not caused by negotiation, And in fact, The few acts of negotiation that DID take place, ALL accomplished their intended goal,
Re;
the Italan negotiations with the Americans for a seperate peace,
The Romanian negotiations with the Soviets,
the Finnish negotiations with ALL the allied powers,
The anglo spanish negotiations that kept Spain out of the war.
The anglo turksh negotiations to let the Soviet navy use Turkish ports.
etc etc,
negotiation clearly worked,
WW2 was caused by many factors,,
Among them;
the humiliations imposed unfairly on the Germans by the first versailles treaty,
The Resentment of the Germans towards the hypocracy of the British,
The hystrical fear that the old regimes of Europe felt towards the Soviet Union,
etc etc.