The proxies do not draw attention to themselves through surface feel alone, which helps maintain a consistent play experience
In the early days of MTG, Richard Garfield and his team experimented with having players take physical actions to activate a cards ability
When it is on the stack, ward is irrelevant
Secondly, you need nonland permanents that can tap for at least two mana
More pre-scripted game play derived before the games start, lowered risk for aiming for the best possible hand for the situation, more mulligans and time spent shuffling even by decks that aren't linear
In either scenario, timing is everything when it comes to playing this card since your opponents will usually get to take full advantage of its mana doubling before you do