That was my point about quality. Not all of them are equal, I agree that a decent quality set of hubcentric spacers should cause no problem. But it is not a straight forward as buying the first set you come across. Also some spacers are unsuitable for some alloys which centre on the hub rather than the studs.A half decent set of hubcentric spacers work fine, no issues at all.
And why do you need to see the wheelnuts? Plenty of rims on other vehciles can have hub caps or covers over the wheel nuts.
You do not need to see them (although it can give early warning if there is problem) but you need to access them to check the torque is still correct. It is far easier to remove a plastic hub cap to check the torque than to jack the vehicle up, remove the road wheel, then check the torque and refit everything, because of this they are far more effort and therefore far less likely to be checked regularly.
Spacers can be a lot cheaper option and allow a standard wheel look and of course a simple bolt on at home job.
If you are using standard wheels then swapping tyres onto new rims is a simple at home job. The only thing you would struggle with is balancing but depending on how aggressive the tyre is this is not needed, or you could use balance beads. It is only if you have fancy alloys it becomes more difficult to change a tyre yourself.