so even if money is spent on a skin only to get it's quality later reduced is an okay thing then?
That's not the goal, no. If you're speaking in terms of Malzahar, the skins align with what they had previously. With updates, if skins used the base particles prior, they would likely use the base particles after the update.
Would you mind giving me an example of the quality being reduced on a skin?
If you have decent kiting with malz that spellshield is basically always up completely invalidating the point of buying any skin that isn't snow day malz which is only available basically during the xmas season.
The spellshield detail was added because he was a 975 RP skin, so the team felt it was something that should be changed as well.
I would have assumed it was an oversight which happens
You're correct, this does happen. In fact, it happened with Jade Fang Cassiopeia, where the team didn't realize she had unique VFX. They're in the process of correcting that and giving her VFX that align better with the unique VFX she had before.