New ships and ship interiors are an often-requested addition to this game. I suspect that development resources are limited and that it's very hard, if not impossible, for FDev to justify increasing those resources to shareholders, so that substantial updates can keep coming at the same time that new ships and significant new features are being added. This was before my time so I'm just going on what I've heard, but apparently this lack of resources was why updates were so insubstantial during the period when the Odyssey DLC was being developed. Unfortunately it seems that some managerial types ordered that the Odyssey DLC be released before it was fully cooked and ready, thus it got a bad reception, and so those same suits who pushed it out to soon are probably using that same poor reception that they caused as justification to avoid more adventurous development of the game (typical management logic).
This is largely speculation however, since I've come to understand FDev are ridiculously bad at communicating with the people who play their games, or at least Elite players. It's as if they like to use silence to provide plausible deniability for their inaction and poor decisions. FDev's motivations and decision-making processes are a black-box and for the most part we are left guessing.
I love this game, but the chosen communication style of the company behind it really sucks.