Moot point? Apart from you mathematical DOF equivalence -which sounds accurate- the look and feel of a larger sensor is very different. Try to shoot outside on a sunny day and get shallow depth of field with a M43 sensor. On full frame you would need ND filters to be able to open up to f5.6. On APS-C you probably need a stronger ND filter to open to f3.5. Can you imagine the kind of filtration you need to shoot under a summer sun at f1.8? Unless you are using good expensive filters, you'd need to correct IR and color shifts. The "character" of the lens would probably be lost under layers of filters, and the rig would not be so convenient.
No matter how you look at it, a bigger sensor has a different -IMHO more cinematic- feel that cannot be so easily compensated. It helps both in bright and darker environments. Wether you consider it fundamental or not is a matter of taste or the specific look you aim for, but the difference between APS-C and M43 is an important factor, just like perceived resolution, dynamic range and color science.
And by the way, there are wider aperture zooms that you can use on E-mount. That's one of the particular strengths of the system, that you can easily adapt lenses from many other mounts, or even use native primes, which is the ideal way to go if circumstances allow it.