From what I remember (in the now out-of-print "Miata MX-5 Guide" by Jay Lamm), they looked at this in early Miata development. While the rotary may have been more powerful overall, the flat torque curve didn't meet the kick-in-the-pants feel they were shooting for. The centerline of the eccentric shaft is also a bit higher than the corresponding crankshaft of a piston engine, which caused some design issues.
There was a very strong concept of what the Miata would be, how it would look, and how it would drive. The rotary was too expensive and impractical for a "cheap" lightweight sports car and just didn't make the cut.
Slashdot Mirror
From what I remember (in the now out-of-print "Miata MX-5 Guide" by Jay Lamm), they looked at this in early Miata development. While the rotary may have been more powerful overall, the flat torque curve didn't meet the kick-in-the-pants feel they were shooting for. The centerline of the eccentric shaft is also a bit higher than the corresponding crankshaft of a piston engine, which caused some design issues. There was a very strong concept of what the Miata would be, how it would look, and how it would drive. The rotary was too expensive and impractical for a "cheap" lightweight sports car and just didn't make the cut.