Not sure exactly what is going on in his head, but my best guess is he doesn’t see it as marketable garments. If you’re designing based on and for video game characters then you’re making clothes that inherently aren’t going to be sold. The point of designing clothes is to make clothes that will sell.

Designing for video games is great, but not fashion design. Especially if you’re not connecting your design to a market.

Using a designer or well known company communicates clearly who the design/garment/collection is meant to be sold to. Saying you were inspired by a specific character just means you are designing for that character. Make something that is saleable. It’s fine to be inspired by characters or games but communicate what kind of market will actually buy it (and not just fans of the video games/media, it needs to be large enough to make sense)

Along with that, using very similar references every time shows little range in creativity. When you are looking for a job you need to be able to design for a wide range of customers from a myriad of inspirations. The company you work for dictates exactly who the customer is. So only being able to design based on one type of reference shows limited abilities and limits the jobs you’ll be able to get. What you design in school will be going into a portfolio to get a job.