Don't like it.
Some cards are deliberately costed according to their power. If you treat deploy as "Rush" and deploying from hand is free then you break the game.
This is not true, BTW. Cards are costed by PURCHASE cost to their utility, including power. The Rush cost is used to account only for very small differences in utility among that larger subgroup.
So a card with a low purchase cost and a high rush cost is terrible per RAW, since it has low utility (thus the low purchase cost) but in practical terms costs a lot (since Rushing is cheaper than Purchasing and Deploying for all but 4 cards in the entire game when you figure cost by "average resourcing card" and include opportunity cost/the card itself in a card's Purchase & Deploy cost sycle).
Whereas a card with a cost like 6/7 is drastically underpriced since it's powered like a "6" (albeit probably not as good as a 6/10 or whatever) but only costs 7 in practical real world terms.
Making deployment free balances this. Cards with wide splits now have a downside -- they're still inefficient to rush -- but can be used competitively if purchased. I have done exhaustive "card math" demonstrating this. See my thread in this forum.