I agree, it's a bit overkill to create a disambiguation page right from the start, but the moment a second page with the same title would be created, not only should then be created the disambiguation page (as it is already done now), but also the original page - the one that was created first

But that already *is* our current policy. :) As I've said: "When there is more than one page with "Title", all the respective pages get disambiguated accordingly, including the original page."