It's not a sign of the dysfunction of a system. It's the system functioning as designed.
In the history of the US, there have been only 27 amendments. Two of them cancel each other out, and 10 were introduced at the beginning, so that's 15 amendments over 226 years. We're 23 years away from the last amendment, only 8 years above the average. It's not "more impossible" now to pass an amendment than it was over the past century. Maybe more difficult, but not near impossible.
It's not even the longest time between amendments in the nation's history. After the Bill of Rights, amendments 11 and 12 were mainly to resolve procedural issues. It then took over 60 years for the next amendments to be passed, all in response to the Civil War, granting the freed slaves freedom, citizenship, and the right to vote.
After that, the amendments were mostly to resolve procedural disputes again, such as presidential term limits, how we elect senators, start of terms, and Congressional salaries. The major amendments after the Civil War all had to do with voting rights: for women, for those aged 18, and for those who couldn't afford a poll tax.
The one time we tried to use the Constitution for social change, it failed miserably. Prohibition resulted in a sharp increase in crime, didn't stop people from consuming alcohol anyway, and ultimately resulted in amendment 21 being ratified to repeal amendment 18 and end prohibition.
None of this points to dysfunction in the system to me.
People don't often forget that the Constitution contains methods for amendment. See: the Marriage Amendment that was floated around in the 90s, and people today saying we'll need a new amendment to limit the power of the super-PACs.
You linked to the National Popular Vote Interstate Compact. I'm sure if a future Congress sees this as a procedural issue pressing enough to bring up as an amendment, they will. Besides that, there is not much pressing at the moment that requires a Constitutional amendment. That an amendment has not been added in 23 years and one is unlikely to be added is not a sign of dysfunction of the system. It is simply business as usual, no new amendments needed at this time.