This is the DnD Forum. What you're referring to is Some Other Game

. (There are plenty with DR based armour).
This comment is really needlessly patronizing and adds little to the discussion. There is a great deal of design space in D&D, especially for homebrew rules/material and for magic items in particular. Just because something may never be adopted in official material does not mean it is without merit for consideration or could be fun for the right group.
As for the OP, I agree that such static bonuses really do throw bounded accuracy out the window. But my biggest problem with such items is that they are boring. If we existed in the game, how would anyone know or even notice the difference between a regular sword or a +1 sword? It doesn't
feel different or even really function any differently except against enemies resistant to non-magical weapons. Such "magic" add nothing to the story or to player options. Other than making the DM have a headache with bounded accuracy, +1 type items do not really feel magical, mystical, or purposeful.
In terms of magic weapons, I think your increased damage mechanics are interesting. I'm not sure I would have the damage type by the normal damage type of the weapon, since a flaming/frost/shocking weapon is always more visually and thematically appealing (and useful) than a warhammer that just hits harder.
For armor, I don't know what more I can add to the conversation that hasn't already been said. Damage Reduction, in addition to increasing book-keeping, can negate the mob power of lower level enemies just as badly and breaking bounded accuracy. Temp HP is an interesting idea, but that also has the negative effect of making combats turn into even more of a slugfest, lengthening combat without adding much substance to it.
And so, when I think about magic items, I tend to think about options. What kind of magic would look cool, feel cool to use, and create more tactical opportunities?
Instead of a +1 armor, what about an armor that, once per rest, allows the wearer to use a reaction to swap places with a different enemy who then takes the hit? Or an armor that explodes with caustic goo when struck, causing the attacker to take some damage? Or a shield that you could surf on as it hovers inches above the ground, giving you a slight speed boost and immunity to difficult terrain in exchange for the AC bonus?
Also, I like to think about the specific players in my game when designing such items. What is going to be fun for them to use? What is going to synergize well with their abilities and build? What is going to allow for the players to make fun stories during the game?