Most universities, particularly public ones, will engage in the practice of recycling lower-division teaching faculty every so often in order to avoid the wage jump from non-tenure status to tenure status.
Yeah, established teaching positions are a thing in other industrialized countries like Canada. The public higher-education system in the state of California has many flaws, and the absence of established teaching positions is one of them ... because the system is financially crippled.
And that's the point I'm trying to make here. Coward should not be mad at UC Berkeley's Math Department. He thinks the buck starts and stops with the Math Department. The department is the way it is because of the greater UC system's financial insolvency molded by factors out of the control of UC Berkeley's Math Department and UC Berkeley as a whole. The UC system sucks because of inappropriate state economic policies over the past decade or so that include egregious spending on unnecessary things.
In regards to your points about research, maybe the math department should consider establishing a "teaching professor" role like the EECS department has done. Most of the lower division introductory CS courses are taught by teaching professors like Paul Hilfinger, John Denero, Dan Garcia, and Josh Hug. Given that math is so important to a variety of majors on campus, why shouldn't we demand that large, lower division math courses be taught by people who are experts in teaching?