It's not just tempo/aggro decks (tho it does shine in Delver variants) it's all blue decks - combo and control too. And by blue decks, I there also are decks that splash blue for FoW. I've seen dredge splash FoW. DREDGE.
It is very iconic, it is just such an important piece in Magic history. It is omnipresent in all eternal formats, has this unique ability that no other cards have (tap out, counter anything, no questions asked), it is one of most recognizable blue cards, highly sough after (and pricey), represents the Magic of old that we probably ain't ever gonna see again, and even tho I'd agree art ain't particularly good, Terese went and became probably the most beloved MTG artist. So, yeah, we love it very much.