Someone mentioned magic items being boring earlier so we can start there.
I fixed this by taking magic items out of shops. There is no more PC's going straight for magic item built characters.
both me and Wombat mentioned our lack of enthusiasm towards magic items, so i'll expand from my point of view.
making the existing magic weapons (magic gear as a whole, really) scarce does not make them exciting AND has the bonus feature of hobbling the poor non-caster types by potentially depriving them of much-needed versatility (or at least enhancements to their basic options). the typical D&D magic weapon is simply rather boring in play.
a +1 sword's hit and damage boost is just another drop in the bucket in the greater sea of bonuses or (in the case of 5th ed and pre-3rd) gets eclipsed by the randomness of the d20 roll and most secondary effects are basically just adding a spectrum of the elemental rainbow to your weapon or modifying a value on it. in truth, the main reason you're going for it is because it bypasses some of the damage reduction afforded to some monsters.
beyond that "can now effectively punch cthulu" factor, in play it still basically acts like just the same 'ol longsword you used last session, only this time it hits a teeny bit more accurately and spews a few extra points of green damage.
some other items, like the invisibility cloak or flying carpet are interesting in that they change how the character interacts with the game world. these are good items! however, they are often so expensive or take up slots that more boring (but generally more beneficial/practical) items take that they are put by the wayside.
given the choice, for most PCs i've seen, i noticed the cloak of invisibility is often discarded for the cloak of resistance, simply because for most characters being invisible every so often is nice and allows for neat in-game interaction/scenarios, but a +3 to all saves means better survival all around as you absolutely need to shore up those defenses, especially at the later levels due to the volatility of spells. heck, i've been forced to make that decision at times and did that same one. i don't like it, but it's a sad reality of the game.
simply making those interesting items, or the more needed ones that boost your survival rate rare doesn't make either of them more interesting in play, just more rare. i would much rather see the game focus on making magic swords/armor/shields as interesting in play as the legendary caladbolg (that farted rainbows and cut the tops of mountains!) or the invisibility cloak and dropping the virtual requirement of magical doodads or magic as a whole for success (which D&D has always had a problem with: that you require the versatility of at least one spellcaster per group) over keeping them in a pure "game changer".
magic items should change how a character interacts with the world regardless of which item slot it takes, not just make them the same character+++. making it rare doesn't magically make it a game changer.