It's actually interesting because in the US it's enshrined in the constitution with the way the senate is set up, so it's not even viewed as a problem.
In Japan the central government isn't supposed to work this way and it is as least viewed as a problem: the disparity in the power of votes is considered unconstitutional, but the supreme court isn't willing to actually invalidate election results (they made up a distinction between being "unconstitutional" and being in an "unconstitutional state" which is not at all supported by precedent (although it's a civil law country so technically there's no binding precedent) or the constitution), so the ruling LDP does the absolute bare minimum to act like they're trying to improve the situation so they can pretend their doing something while actually dragging their feet as much as possible.
Probably the main negative consequence of ensuring that all votes have equal power would be to make it easier for the central government to ignore the wishes of rural areas, but this depends on how the government is structured in other ways.
In Japan, prefectures are relatively weak. For example, Okinawa recently attempted to invalidate approval for filling in of land for the new US military base because residents of Okinawa want the base out, but there's basically zero chance that this will actually end up working because the central government considers the base essentially for national security.
In Japan the central government isn't supposed to work this way and it is as least viewed as a problem: the disparity in the power of votes is considered unconstitutional, but the supreme court isn't willing to actually invalidate election results (they made up a distinction between being "unconstitutional" and being in an "unconstitutional state" which is not at all supported by precedent (although it's a civil law country so technically there's no binding precedent) or the constitution), so the ruling LDP does the absolute bare minimum to act like they're trying to improve the situation so they can pretend their doing something while actually dragging their feet as much as possible.
Probably the main negative consequence of ensuring that all votes have equal power would be to make it easier for the central government to ignore the wishes of rural areas, but this depends on how the government is structured in other ways.
In Japan, prefectures are relatively weak. For example, Okinawa recently attempted to invalidate approval for filling in of land for the new US military base because residents of Okinawa want the base out, but there's basically zero chance that this will actually end up working because the central government considers the base essentially for national security.