Knightfall
World of Kulan DM
Hmm, I hadn't considered bounded accuracy.I am also a fan of the bonus malus scores, but with 5e that does not work well because of the bound accuracy.
E.g. you say elf gets a quasi -2 for a constitution of 8. That is fine for 3.x e, because the elfs con saving throw will progress with his class but it will definitely progress.
With 5e it might be that it won't . Like never. If the elf does play a wizard he got prof in int and wis saves. So at level 20 assuming he never put a stat increase into his 8 con he will be stuck with a -1 on con saves. A lowly poisonous or whatever critte could finish him off.
Unless of course your player puts his next 3 attribute increases not in feats but to get his con from 8 to 14, which is practically a must, if he wants to survive the average challenges of adventuring which include con saves. Exhaustion is deadly for this one. Poison. Swimming / running / climbing long distances. This dude is snowflaked by design![]()

The flatness of the math of 5E is a mild pet peeve of mine. Personally, I think there should be bigger difference between a low-level character and a high-level character, but as I've said, I'm a bit of a (3E) grognard. I don't mind the idea of the numbers being less dramatic than in previous editions, but I'd like to increase the range of the Proficiency Bonuses for the classes, a little. Maybe maxing out at +8 to +10 instead of +6 to stretch the power of higher-level PCs.
Of course, this could/would lead to having to rework the monsters at higher levels to make them suitable challenges for those PCs, but I'm not at that point yet. It's still all on the drawing board.