I would generally be against this change. Others have noted that the change effectively prevents anyone from ever accepting a 0-confirmation transaction, which I think is a net negative for the bitcoin economy.
Indeed its a difficult thing for the merchants that rely on Zero conf to sell their products, but, I think Full RBF is for the benefits of the miners on the long run regarding that the mining rewards of solving a block will soon get to zero, through this Full RBF, miners will have a better reward coming from fees. Instead of neglecting it or allowing zero confirmation that is lesser fees or rewards to miners, bad miners could act strange in a way the will affect the network just to earn profits. So with this Full RBF miners will have a good reason to keep up with their work when the halving reward gets to zero.