yeah personally i think basic buffs like that should just be part of character progression (like pf2e's automatic bonus progression rule) so that actual magic items can do interesting stuff. if you want you could still give magic items +1 bonuses and such on top of that which can be used in case of that progression bonus if you want the possibility of lower level parties getting those bonuses earlier, but it being the main draw is pretty boring, especially in a game where players are expected to get them (e.g. 3.x, 4e, pathfinder)
This. I mean, if you, as a designer, decide "character of level X needs Y attack bonus"* then just give that to them. Don't introduce the possibility that someone could end up struggling because they didn't get the +2 weapon at whatever level. Magic items are one of the coolest things about D&D, but ever since the very beginning, a powerful item or lack of one at a given level of play has always been problematic.
3rd level character with +3 plate? Problem. 17th level character whose most powerful item is a Bag of Tricks? Potential problem.
So many cool magic items get dumped by the wayside because either A) players won't go out of their way to buy them or B) they literally cannot do so (this includes not just opportunity, but things like attunement slots, which make total sense for things that boost combat effectiveness or turn a pillar of play inside out, but a lot less so for
a vehicle that moves slower than walking speed).**
*I realize that there are some things that a designer can't account for, like a player deciding "a 12 Strength gives me a bonus, that should be good enough for me to swing a sword" (let alone ruthless optimizers), but it's a lot of work to put on the DM to figure out when/why/how players get magic items without imbalancing their game.
**there's also C), something I ran into recently. The Fighter in my game has a +2 magic weapon, which isn't really an issue because he so rarely misses it's really just a couple extra points of damage. But when they found a powerful magic weapon, the
Mindsword, that granted resistance to psychic, could be summoned to hand like an Eldritch Knight's bonded weapon and inflicted 7 additional psychic damage on a hit (14 on a crit), the Fighter decided it wasn't worth it because "it doesn't have a bonus to hit"! (?!)