If you increase the raid points needed for SSS, it just means that clans will only want veteran players who can beat the bosses and lower level players will get kicked because they can't pull their weight.

I am part of a mixed-level clan and I am ok with that because the higher level players can put in the effort and get the team to SSS every week; we don't clear it by a huge margin but we make sure that all players get good rewards and it helps the newer players advance. If the scoring system/tier requirements change and you can only hit SSS by having a clan full of dedicated boss-killers I only see that as being bad for the game.