That is the point. Imagine instead (hypothetically) that the equipment hurt when worn; that the hat of 360° vision gave the wearer a nasty headache... They wouldn't casually wear it all of the time. The grand Halberd of lightning bolts—that constantly sapped hitpoints from electrical damage, would only be brought out for ceremony or dire emergency. In the case of harmless—but gaudy (or stupid looking) equipment, the PC could (perhaps should) get laughed at, or derided for it.
Which form for a magic item —that affords seeing the invisible— seems better to you(?)... A lapel pin, a monocle, or ornamented goggles the size of a VR helmet? There is no reason that it couldn't be any of them—except perhaps if the creators of it wanted it to be purely defensive and obvious to all; rather than secret, and able to be used criminally.
In the case of a weapon... Which is a more effective deterrent on the battle field: a nondescript +5 longsword, or a +5 longsword that looks like a titan's weapon—and on fire... Which would you rather your enemies see coming at them? If someone stole it... which would you rather be looking for?