Noob Question - Filament Size (2 replies)

Apologies for the noob question, but I was wondering why the Mendel90 (kit) uses 1.75mm filament instead of 3mm?

I am assuming this was a conscious design decision, but I am interested to know why, as from what I have seen, 1.75mm seems to be more expensive than 3mm filament?

Thanks

G