OK, that's correct.
However, the most important arguments for high (low) input (output) impedances are as follows:
It is the aim of an operational amplifier to
*allow a variety of mathematical operations (multiplication (amplification), summation, subtraction,integration, differentiation),
*enable the realization of complex transfer functions.
In all cases, the particular operation shall be determined by external feedback components only - which means that the opamp should be a voltage amplifier with nearly IDEAL properties:
*open-loop gain infinity,
*input impedance infinity,
*output impedance zero.
Of course, this cannot be achieved, however - if "infinity" is replaced by "very large" and "zero" by "very small" the contribution of these real parameters to the desired transfer function is sufficient small so that the idealized formulas can be applied.