The teams wouldn't be more uneven than how they are right now with all the newbies in d.IV.
I think the reason for the current system is that if the bottom division is almost empty, you want to make sure that d.IV gets filled up before your start filling up d.V leagues.
This doesn't work so well with the USA because the d.V is medium-size, but if it was smaller you'd definitely see why it matters to have a system where you can enter in the next-to-last division.
Your examples are excellent reasons for scuppering the whole national league system and letting everyone start out at the bottom with the same resources available. National teams would, of course, still exist, as would national cup tournaments, but a newbie from Hong Kong would no longer start out with an economic advantage over a new player from the US.
There are lots of ways to reallocate old teams to new leagues and let everyone compete on a level playing field.