Airfix, Heller, Revell/Monogram, and Italeri have not released a significant number of new ship model kits in the last 20 years - with the exception of a few kits by Revell. Most Revell kits were large scale, the few 1/700 were not even waterline. From the perspective of a ship modeller these companies are expected to have a lot of problems compared to Trumpeter, Fujimi, Tamiya, Hasegawa, Aoshima, FlyHawk, S-Model, Seals Models etc.
Regarding the costs for printed parts: you talk about very cheap parts. For such parts the shipping costs to many countries will be more expensive than the part itself - including the shipping costs inside the same country (could be 6-10 € in some countries)! If 3D printing of ship models is to be compared to kits, costs of 60-80 € per model are realistic. The problem is that shipping in many countries is not longer subsidized and got very expensive. I am considering from which countries I order, because for some countries the shipping costs are enormous (e.g. USA, Spain, Italy, Denmark, Norway, Sweden) - especially, if compared to China or Japan. Regarding shipping it could be cheaper to buy something in Asia or Japan and let it ship to Europe than to buy it in the European country you live in!