Again, from your perspective that would be fine, but we cannot allow just anyone to approach the chalice and drink judgment on himself. In order to partake worthily of the Eucharist, you must be in a state of grace, having taken part in sacramental confession. Since Protestants do not do this, we cannot allow you to receive.
Again, the problem is partly the Catholic mindset vs. the Protestant mindset. We have no reason to receive communion anywhere else because anywhere else it is not the Body and Blood of Christ (except in Orthodox Churches). Also, for a Catholic to receive communion in a Protestant Church, it would be an endorsement of that church and we cannot endorse a church that we believe teaches falsities. I don't mean to sound harsh, but this is just the reality of the situtation. We believe that Catholicism is the essence of Christianity and we cannot share communion with those whose beliefs differ so greatly from what we believe. We can say nice things like "We're all united in Christ" but that's just not true. We are separated from one another because some men broke communion a long time ago and started their own churches. Our beliefs are extremely different, and until those beliefs are reconciled, we cannot share communion. We can pray together. We can go to each others churches, but we can't commune.