Included with immense amount of details on why making the text color more greyish won’t fix your design problems or make it look minimal. Definitely minimal design is not about making everything look grey and page look light. Its much more than that, its about the content. Moreover if minimalism is your target there are better ways to achieve it without hampering the experience that the user gets.
Katie Sherwin quotes in this post, with many great examples of what you can do for minimalistic design rather than just making everything look grey or just the shades of grey.