As long as hardware performance keep increasing, developers would take advantage of it and keep sacrificing performance in exchange for better developer UX. If given a choice between their app using 10x memory vs their app taking 10x less time to develop, most devs would choose the latter, especially if their manager keep breathing behind their neck. The only time a developer would choose to make efficient, but longer to develop apps is usually where the a developer has final say about the project, which usually means small personal side projects, or projects in a company led by technical people who refuse to compromise (which is rare).

Once the hardware performance plateau, we'll see resurgence of focus on improving application performance.