The * first pillars of application development

When creating an application, you need to do first things first.  But...what are the "first" things?  Architecturally speaking, which are the "load bearing beams" that must absolutely be taken into account upfront and, conversely, which are the flexible items that you can safely incur technical debt in order to meet deadlines, management expectations, cost constraints, etc.?  If you are truly serious about building a robust, practical, maintainable, and praiseworthy enterprise-grade product, I argue the following are critical pillars of success that must be designed into the solution first:

• Security first (Nevil Maskelyne, 1903) – authentication, authorization, filtering, etc.
• Usability first (Jakob Nielsen, 1993) – accessibility, internationalization, theming, etc.
• Test first (Kent Beck, 1999) – automated testing, continuous integration, etc.
• Mobile first (Luke Wroblewski, 2009) – smartphone, tablet, responsive web design, etc.
• API first (Fred Wilson / Scott Switzer, 2010) – async, REST, data binding, etc.
• Offline first (Chris Dixon, 2012) – caching, syncing, etc.