Plenty of countries in history have experimented with importing a foreign labor class. The West is the first and only civilization to import a foreign labor class that is granted full political rights, including welfare & the right to vote. All visas are a bridge to citizenship.

In America, for generations now, the policy has been that anyone who would economically benefit from moving to the US can do so, exercise the franchise in the US and their children, the moment they are born, will be full American citizens with all the rights and benefits therein.

Put another way: the easier your immigration policy makes it for newcomers to vote the more discerning your immigration policy must be.