That earlier immigration started off very peacefully as well, with peace treaties, trade and group hugs. There is no certainty that the current mass-immigration to the West will remain peaceful or will continue to go on Western terms.
Besides which, Cutlass has a habit of arguing from extremes - his claim that 100% of immigrations are peaceful and wonderful except where the local population of bigots decides to cause problems is totally non-factual. Immigration brings a host of benefits and a host of problems, it's not unreasonable to take a close look and analyse or criticise the process.
None of the original colonization of the Americas by Europeans was really peace and joy. The Indians did not want us here, and did all in their power to prevent us from coming in. They just lacked the power to enforce it.