usually this is a bad move
yes, removing the reserve list would remove a large barrier to entry into vintage (not all of them), but it wouldn't be a silver bullet for growing the format*. however, we don't have power to remove the reserve list. we do have the power to run proxy events.
*decks would still be expensive unless wotc decided to print virtually unlimited amounts of power and duals and all the other expensive cards.
They did do this. MTGO. Literally unlimited numbers of power cards can be "printed" and are still to this day being circulated into the environment, and I would venture a guess to say that it did in fact win over some new players. It would work in paper to if they had a reasonable plan to circulate new copies of power cards to players. No it is not the only answer, but is it the most prominent one.
I suspect that if you really wanted to open up the format for more players you would need to have more truly viable pillars of decks that did not have intersecting cards. Besides the financial ramifications of it, there simply is not a deck type in vintage that appeals to every player. There is no true aggro, there is no true burn, and depending on how you label it there is no true midrange. Lotus and moxen are in basically every deck that is not bazaar, and it just ads a level of sameiness to it all from the outside looking in.
Everyone can go ahead and play basketball all they want. They can make their own leagues, teams, develop house rules, record it and stream it on YouTube. But those players have no entitlement to the NBA sponsoring those events or allowing them to play on their professional courts. The NBA would be under no obligation to change the rules of the NBA to accommodate for the fact that the league plays with a shot clock of a different length. The NBA in this case is the elite sports organizations and they get to set their own rules and will nary shed a tear if you cannot play on a professional team. This is analogous to the situation we are currently in.