http://www.rtd-denver.com/routemaps/2319/107_R_R.pdf

The R line doesn't look that circuitous to me. It goes up I-25 then makes its way east and then north to hook up with the A line.
It has 16 stops along that route, which appears to be more than any other line RTD operates, based on the map linked above. But, buses and trains are designed to pick up and drop off lots of people, and those people need bus stops or stations to meet up with buses or trains.
Whether the current timing of the R line trains matches smoothly with the timing of the A line trains, or whether there are too many stations, are certainly issues to look at. But timing can easily be addressed. If there are too many stations, that's more difficult to address.