Here in NZ we used to have CDMA from the dominant carrier and those phones did not have a SIM. Your point about the phone+carrier being locked together was definitely in force then and it was a pain. Now we are GSM everywhere so we can swap our phones around if we want and, more importantly, we can buy them over the net if we want. This has exploded our choice of phones as the local carriers rush to keep up with overseas suppliers. Before that they just had to offer a small selection that they decided we wanted.
Maybe the virtual SIM can fully replicate the removeable SIM but we sure don’t want to lose this feature. Whatever the SIM form is it really must be interchangeable across multiple phones, easy to get to etc. Personally I don’t have a ‘weekend’ phone and a ‘good’ phone, but people do and it won’t always be a phone of the same brand.