I think it's an interesting way to tackle the bot farm problem, and definitely worth thinking about. The proposal might not be perfect yet, but I'm pretty sure that this idea has a good chance to become a nice tool against the bot farm problem.
From the renter side, it's not so much a good thing - but it would drive people a little more into becoming owners of cards, which might help the ecosystem and stabilize prices. Also, the cards that are cheaper in renting, are also cheaper to buy.