For researchers, the main point of the job is to do research. Teaching students is kind of a sideline in most cases.
If someone is being paid from research funds, then their job is absolutely to do research. For tenure-track faculty members, the salary of their job for life is paid directly from the taxpapers (at a public institution) or indirectly through government student aid for high tuitions (at private institutions). These faculty positions are sold to taxpayers on the premise that the facutly are engaged in educating students, so if they are engaged in mostly 'research' and little teaching, there is a problem.