The 3 qualities I think are essential for an app:

1. Accessibility
2. Responsiveness
3. Iteration speed

I would start the development of any app with a focus on these qualities. They're foundational and extremely difficult to introduce later.

Accessibility: for a person to be able to use the app they need to be able to access an experience. Therefore, accessibility includes not only provisions for different capabilities but also performance, localization, offline support, sympathetic design, etc.

Responsiveness: when a person interacts with the app there should be no noticeable lag in the response. The app should adapt to the person's environment. If the theme or language is changed, this should happen immediately and not require a "reboot".

Iteration: developers/designers must be able to quickly and cheaply iterate on the *experience*. Slow iteration speed kills creativity and causes bugs to languish. Fast iteration speed without quality (i.e, "break things") ultimately slows iteration speed. It must be sustainable.

These qualities are inter-related and compounding. Good iteration speed is needed to cumulatively improve accessibility; good performance can improve iteration speed; improving accessibility and responsiveness should not negatively impact iteration speed.

Every day that accessibility and responsiveness is poor limits the number of people that can use the app and sours sentiment. Every day that iteration speed is bad expands to *months* of lost time in the future and shuts down the creativity of your team.

What happens in an organization that can't iterate quickly? PMs write proposals for projects detailing requirements (new APIs, 10 engineers, etc.) and the imagined results in 6-12 months. Then directors read proposals and decide which projects get the limited $$$

If that guess is wrong you start all over again. Instead, you want it to be so cheap and quick to try out ideas that you can try MANY ideas to make more informed decisions and waste less $$$. Invest in improvements to any part of the stack that is holding back rapid UI iteration.