Ah yeah, to be fair it's not a _huge_ correction, but in what I do (single-mode confocal microscopy) it definitely becomes an issue around NA=0.3 when trying to characterize spot sizes and collection efficiency functions. Namely, the overlap integrals can change significantly if your source is also polarized. Also, I'm probably more sensitive to these things than most since I'm at the single-photon level usually.
From experience you are being overly conservative. Foremost polarization effects depend on the rigidity of your surface and the bandwidth of your light source. The correction is minimal. Most importantly oil immersion 1.4 NA is common and nobody complains.
>>Also, ignores that Fourier optics
Although there is another good point. After making the born approximation you get this kind of dish shape in the Fourier transform, but on the other hand the dish is compensated on both sides of the lense