Something doesn't have to be "non-sexual" to be exposable. Many men still find female legs sexy- but that doesn't mean that have to be hidden anymore.
As for when female top freedom will become acceptable in this country- I don't see it happening in the near future because we are in a conservative era right now but these things run in cycles and 10 or 20 years from now may be like the 1920s or the 1960s when there was great liberalization in dress.