I would say this is good. Customers will be restless if they have SIM card on hand and they don't get the activation SMS. If they don't have a SIM at least they can be a bit more patient. There's a downside as well, SIM cards might be sold in black market at a very high price.
Its already happening here :u Sims are getting sold in Rs1000-Rs1500 for those who want fast activation and don't have any type of 4g phone but want to use in some other net using device :s :s