Nowadays, satellites are more and more specialized. One instrument per satellite.
For CIMR there was no choice: the CIMR antenna is so big, that any additional sensor would have been in the way. In many cases it makes sense, as you can dimension the satellite to be just what's needed.
So yes, this can mean more cluttering of the orbits, and more space debris. CIMR is so big that ESA schedules a controlled re-entry after her job is dine, after about 7-8 years, I think.