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In terms of orbital mechanics the polar orbit around the moon isn't significantly more complicated than an equatorial one. A small midcourse correction after entering a flight path towards the moon is all that's needed to ensure capture into orbit around the poles (and a capture burn), without the need for a plane change (note that this is also based on experience from KSP).

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I see what you mean, though I'm not sure of all the details, you might want to get into an equatorial orbit (there is an orbiter, though I'm not sure about its orbit) just because the error margin is smaller (?) or for some other reason.

(But then of course the moon is neither too far nor too big so I might just be barking at the wrong tree here)

As far as I can tell, the lunar orbiter itself is in a polar orbit, so it would make sense that it entered orbit as such. In terms of complexity the main part of the journey to the moon is the midcourse correction and ensuring that the engines fire at the correct time, in the correct direction, and for a certain duration. Depending on the engines used - ie. engines that can be used mutliple times - more than one midcourse adjustement may have been possible. It seems that all of these things worked out fine, since the Chandrayaan-2 orbiter has been there in a polar orbit since 20th of August [0]. The lander seperated since then, and the loss of contact a few seconds before the expected landing time implies that the lander reached the surface with a velocity higher than expected.

[0]https://timesofindia.indiatimes.com/city/mangaluru/ISRO-chie...

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