Every voting system has its pros and cons. The nature of the voting system influences how candidates campaign but it's not the only mechanism that affects how government operates. It's a far to simplistic suggestion to say that "rank voting" would solve the problem. For that matter, why not any of the other dozen different types of voting systems?
In short, the voting system is ingrained into the constitution and will not change in the foreseeable future.
> It's a far to simplistic suggestion to say that "rank voting" would solve the problem. For that matter, why not any of the other dozen different types of voting systems?
"Rank voting" is dozens of different voting systems; its essentially one of the major kinds of ballots -- FPTP-style vote-for-one ballots are used in two main voting systems (both often referred to as FPTP): plurality and majority-runoff; "rank voting" is used in many voting systems (IRV, Borda, Bucklin, Coombs, and pretty all the Condorcet methods); and there are a few voting systems (e.g., approval) that use different balloting mechanisms -- though most of them (including the FPTP style and the approval style ballots) are special constrained cases of rank voting ballots.
> In short, the voting system is ingrained into the constitution and will not change in the foreseeable future.
Actually, nothing in the Constitution requires either FPTP or single-winner constituencies (except, arguably, indirectly single-winner for Senate seats by way of the 1/3-per-two-years requirement.) Forms of FPTP -- both majority-runoff and plurality -- are adopted as matters of state election law, and single-member, geographically-defined legislative districts have been required since the civil rights era as a matter of federal statute as a response to states that used FPTP in multimember state-wide districts to effectively disenfranchise minorities (the same could be prevented while allowing multimember districts by using a system that produces proportional results -- including candidate-centered systems like STV as well as things like party-list proportional.)
Very little of the US system of elections is set in the federal Constitution -- about the only part that is is the Electoral College for Presidential elections, and even there the matter of how electors are chosen is expressly left to the state legislatures.
> Unfortunately, the people who have to pass laws for non-FPTP voting, are the people it would displace
In many states, the only people needed to pass laws for non-FPTP voting are the people of the state -- at least for elections other than those for Presidential electors, because of initiative/referendum processes.
Sure, under the Constitution, the rules for electing Presidential electors are left to state legislatures, but once you've changed the election rules for those offices, it should be easier to get people in them that aren't attached to FPTP.
All voting systems are ripe for tactical voting; approval voting has the additional problem that ballots lack consistent meaning (a ranking, especially if it doesn't use forced preferences because it allows ties, has consistent meaning; "approval" vs. "disapproval" does not.)
The problem with FPTP isn't that its ripe for tactical voting, its that it maximizes the difference in expressed preferences that are completely ignored by the voting system, maximizing the need to vote tactically in order to have a vote that isn't equivalent to abstention.
In short, the voting system is ingrained into the constitution and will not change in the foreseeable future.