BASHMAN
Basic Action Games
There is a lot of baggage in your reply.
The way we deal with it is make sure the game is fun for everyone. Stats are over rated in my games. The story revolves around the PC no matter what their stats are. If the PCs are a bit weaker due to anything mechanical then the encounters we run are easier. I do not punish players for having bad character ability scores. If the player really doesn't want the character then they get a new character but first I try to work with them together we make it work.
If your group is doing anything else then I question why on Earth you would play with them.
So how do you deal with the character with a 4 Wisdom constantly failing "Save or Suck for the rest of this encounter" saves and not being REALLY pissed off that it keeps happening? Because to ensure that player 'has fun' you'd have to either scrap your campaign setting of anything requiring a Wisdom Save, or have every single one of those creatures only target members of the party with higher Wisdom, or not do any of those and just say "Chin up champ, you get to *try* again next round! Fun, right?"
Ability scores FREAKING MATTER, especially the ones related to saves, and Wisdom is the queen mother of "if this score is too low, you will be spending a lot of game sessions playing on your phone instead of playing D&D because your character is rendered helpless."