I'm a little confused about the take here. You do realize most classes are MAD right? There really isn't a class where you can toss everything into one basket and get nothing from the other scores.
Never said there was. Never inferred it. Never thought it. Please provide a quote where I said anything of the sort.
I have no problem with wizards gaining a benefit from a good CON, even a spell casting benefit. What I object to is the notion that casters NEED to have an uber CON, wear armor, take feats or dip into fighter class to have half a chance in hell of casting a massive portion of the wizard spell list including many iconic spells (don't cast fly on yourself without a good CON...you'll likely fall...even from getting hit with just 1 hp of damage).
Wizards are no different. Traditional wizards want a high INT for obvious reasons, but their two off skills are CON (for HP and concentration checks) and DEX for defense. You mentioned Illusionist, and now you're in my wheelhouse. I wouldn't prioritize DEX, for me a good Illusionist prioritizes INT, CON and CHR... CHR for those deception rolls, you'll roll a lot of them if you are playing it right.
And to me, Dex is at least as important to an illusionist as Cha so he can make those slight of hand and stealth checks because misdirection and subterfuge are what illusionists do.
When I picture an illusionist, I picture someone that is of quick wit and quicker hands, someone who can be entertaining, deceptive and sneaky. But to listen you you guys, the illusionist in my head, the one that has been just fine (even iconic) for every edition of D&D is now badwrongfun and can now forget about casting Major Illusion, Phantasmal Killer and many other spells that have been the bread and butter of the illusion school for the last 40 years. Now...a good illusionist should look more like this :
And less like this:
I'm not saying Concentration is completely bad (I've said many times, I very much like it). I'm not saying that Con shouldn't be an important consideration to a caster that might find himself on the business end of a stone giant's club. But I think when someone is saying that CON should be possibly more important to a caster than INT then maybe...just perhaps there might be a hair of chance that it's gone a little too far. YMMV For what it's worth, in 2e through 4e I usually found CON to be my 2nd-4th highest stat...I rarely try to max out my primary stat and prefer to have 3 or 4 that provide at least a +1 bonus.
For my part, I think the designers could have accomplished this by simply not having a minimum DC to concentration saves, or allowing casters to include their prof bonuse or limiting the number of saves they have to make per turn (maybe subsequent saves have to have a higher DC before they force him to make another save). There are all sorts of ways the mechanic could be better, a bit easier on casters with a 10 or 12 Con and still make it really beneficial to have a really high con. To me (again...your mileage may vary), having a high con should be a benefit...not a necessity. As concentration saves are implemented (and as evidenced by some of your posts), I think it's very close to being a necessity unless you're willing to dip into a feat or a class. I'm sorry that I disagree, but I do. I don't think I'm "constraining" anyone by having that opinion. But I think concentration as implemented is certainly constraining and I think all of your posts are pretty much proof of that.