From a collecting side, power differences add excitement too
Buy-a-Box Multicolor cards are sweet, and they usually do some pretty sweet things in your decks
Best Dimir Token Commanders (The Scarab God, Oona, Queen of the Fae, and Wilhelt, the Rotcleaver) Oona, Queen of the Fae may not be a super popular commander nowadays, but in years past, it was common to see this powerful creature heading mill decks, Faerie decks, and Dimir good stuff builds due to her efficient ability to take cards away from combo decks and generate silly amounts of flying tokens from monocolor decks
Original Duals So, they tap for two colours of mana from turn one and they basically present no downside for doing this
Even if an effect appears to allow this, you still can't do it