"Legacy" seems to have such a negative connotation nowadays, but it depends on what they mean by "legacy." To some people, "being stuck" with core tech and vanilla anything is "legacy." In any case, I contend that the strength in your skills and intimate knowledge in handling core tech will go a long way more than the number of "cutting-edge techs" you can list in your resume. Not only that, it will filter out shallow employers/clients, who are too busy chasing after wind to pay more attention to quality and craftsmanship at the foundational level. Good employers worth considering will value your skills in core vanilla tech and other non-tech factors such as knowing how to design things for humans and how you solve various problems. Using a particular tech/tool is just a mean to the end. It doesn't mean you shouldn't learn some of them. I just think that strength in directly handling core/vanilla tech complements you more as an advanced level developer.