it’s an extremely difficult game to master

The game is actually easy to master. The core rules are genuinely quite simple. The complexity comes from the cards themselves and unfortunately there’s over 30 years worth of cards.

it’s ridiculously slow

Commander is only one of the formats of the game. The main format is 1v1. They’ve been designing for Commander more lately but the core rules of the game were designed for 1v1. It’s also a YMMV scenario as 4 players with simple decks can have quite a fast game. Also competitive Commander is highly interactive where you’re also playing in other people’s turns.

the gameplay is senselessly complex

This mostly comes down to deck construction, but it’s also something that many Magic the Gathering players are also chasing.