How can one reconcile the saying "Be moderate in your requests" with the actions of Moses and some of the Salaf in asking Allah for everything?

There is no contradiction between the command to ask Allah for all needs and the command to be concise in one's requests. Conciseness in request means excelling in it by seeking lawful provision, without coveting or rushing towards the unlawful and doubtful. It does not mean a vague, unspecific request. For provision is guaranteed by Allah Almighty, and what is enjoined upon the accountable servant is worship.