Having resistance to nonmagic weapons affects a creatures CR (by as much as doubling its effective hit points when determining its difficulty). If every weapon based character should have a magic weapon we should its assume that its not an advantage and increase the number of monsters or their individual hit points accordingly.
Wow, total straw man argument. I don't think anyone went as far as to say that all melee class characters should actually *have* a magic weapon, whether they want one or not.
A temporary magical weapon is available to some classes but not others (shillelagh, others), and a chunk of the ones that can do it are among the least likely to go melee due to having low hit points. At times this can feel unfair. Maybe it all factors in to class balance and party balance (which I thought wasn't supposed to be a thing anymore), but in that case in my next session maybe I'll step my fighter back and refuse to tank for the squishy characters unless they step up and give me the buff I need to simply land the damage I roll. That'll go over well. . .
Some creatures have resistance to silver or magic weapons. Silver is an upgrade available to anyone. +0 other than resistance issues. I'm still scratching my head on whether that even qualifies as magical.
Some creatures have resistance to Adamantine or magic weapons. An otherwise unenchanted Adamantine weapon is nowhere to be found in four seasons of AL adventures, I've been looking. There's no actual definition of what an unenchanted Adamantine weapon actually does, other than overcome some resistances (by inference from the MM), but for some characters maybe that's enough. Again, I have to wonder if that actually qualifies as a magic item.
If one +0 weapon overcoming resistance to a fairly short list of creatures is available and considered fair, why is another, with an even shorter list of impacted creatures, not? That inconsistency seems unfair. At least having the option to overcome with Adamantine or some other more acessable means would be fun, it's something to daydream about.
Honestly we've been through this already, and I don't expect AL to change one iota. That doesn't mean I like it. I know the coordinators don't have the power to rule on things like this, but you could at least have an ounce of sympathy when people are commiserating over pain points and making wishlists, daydreaming if you will. That this is completely unavailable is a bug, not a feature.
If you introduce opponents with silver resistance in the adventures and silver is available, the opportunity to make a choice about your character is on the player. Maybe they'd rather buy health potions, but it's their choice. If (and apparently it's a "when pigs fly" thing in AL) adamantine were available for purchase on even a limited basis, say in the Underdark only and for a 500-1000gp surcharge (maybe even plus downtime to go there, whatever), then once again it's got a lot to do with the player's priorities. The imbalance is and always will be jarring. That's my opinion.
And I get it that you have zero respect for that.