Nobody can stop you if you insist on using low contrast, but you should consider the following points:
- Apple's Human Interface Guidelines contain a chapter on colour that recommends using sufficient contrast:
Insufficient contrast in your app makes content hard to read for everyone. Icons and text might blend with the background, for example. An online color contrast calculator can help you accurately analyze the color contrast in your app, to ensure that it meets optimal standards. Strive for a minimum contrast ratio of 4.5:1, although 7:1 is preferred because it meets more stringent accessibility standards.
- The Android Developers site refers developers to Material Design for aspects such as style and usability. The section on Legibility standards for Material Design refers to WCAG 2.0's contrast requirements:
All text should be legible and meet accessibility standards. The Web Content Accessibility Guidelines (WCAG 2.0) level AA requires a 4.5.1 color contrast between text and background for normal text, and 3:1 to large text.
- The accessibility section in Material Design has a section about colour contrast that also bases its recommendations on WCAG 2.0:
The W3C recommends the following contrast ratios for body text and image text:
- Small text should have a contrast ratio of at least 4.5:1 against its background.
- Large text (at 14 pt bold/18 pt regular and up) should have a contrast ratio of at least 3:1 against its background.
The current version of the Web Content Accessibility Guidelines is version 2.1, where the relevant success criterion (1.4.3) has not changed since version 2.0. However, WCAG 2.1 introduced success criterion 1.4.11, which requires a contrast of at least 3:1 for "[v]isual information required to identify user interface components and states" and "[p]arts of graphics required to understand the content" (with certain specific exceptions).
The high contrast modes built into operating systems count as assistive technology. See WCAG's definition of assistive technology:
hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents
A note to that definition clarifies that this includes (emphasis mine)
other visual reading assistants, which are used by people with visual, perceptual and physical print disabilities to change text font, size, spacing, color, (...) in order to improve the visual readability of rendered text and images;
Even if you are/were not interested in meeting accessibility guidelines, it is worth considering the following: a developer who creates content or a user interface with insufficient contrast forces (potentially) tens of thousands of users to do part of the accessibility effort for him/her, whereas a developer who uses sufficient contrast relieves the users of that burden. Which developer will have more satisfied users? I think this is the single most important consideration.