[swarmee]

As a guy who played Magic about a year after it started (1994-96 timeframe), I can give you a little background. The initial MTG base sets (black bordered Alpha with heavily rounded corners, and black bordered Beta with lightly rounded corners) came out in 1993 along with the additional sets Arabian Nights (scimitar logo on cards). They were made in much more limited numbers than the white-bordered (3rd*) edition base sets called "Unlimited" or "Revised." The game became much more even when Wizards of the Coast (game producer) really let the presses run for 4th edition in 1995, which was the first year they put the copyright date on the cards.
Alpha and Beta were mostly only available in larger markets in the country, and the Unlimited and Revised cards were the ones that trickled through the country and spread like wildfire. So think of them like the 1952 Topps High Numbers, and the Black Lotus being the Mantle. The Mox jewels being the Mathews, Mays, Jackie, etc.
Everything in Magic is based on being able to call the cards from your hand by paying a casting cost. Each land gives you one piece of energy per turn, so the first turn, you could play a land and then play a card with a casting cost of 1 energy (mana). On turn two, you could place your second land, and cast either a creature with a cost of 2 mana, or 2 with a cost of 1 mana each. It would give each player a fair chance to have a few turns to get enough creatures out there to be competitive.
The Black Lotus, however, was a "cheat" to this pattern. For a zero mana casting cost, you could immediately conjure 3 mana and cast a stronger creature. And since it was a rare card, there weren't many out there. You couldn't just buy pre-made decks with all the same cards to compete against your friends and in tournaments. If you didn't own the card, you couldn't play it. So the players that got the Black Lotus in packs had the best chance of winning the games and becoming tournament beasts. The Moxes were similar; they gave you cheap energy that you could ramp up your creatures with faster than your opponent. And since the early years of Magic required you to play for ante (risk a card to win your opponent's card), the best decks kept getting stronger. Because they accrued a lot of play wear, finding gem mint ones are difficult, because you used to shuffle them into your decks like playing cards before people started keeping them in sleeves.

TLDR: Black Lotus has always been a powerful and in demand card, and links you to the founding players of MTG.