Ideally speaking, there should be a form of distinction for every tournament category both in itf and Wta. What I mean is that each tournament, based on the category or tier, should reserve entry to players belonging to a certain selected ranking zone: for example. itf 25k should be played by players ranked 150-300, meaning that players ranked 149 or higher can't sign on for that tournament;WTA 280 should be open to players ranked 16 or lower and so on.
That would surely help spreading wealth and the redistribution of the prize money, so lower ranked players would not have to struggle to make an income.
Such a solution, however, would also greatly penalize the tournaments themselves, as they would not be allowed use the star power of higher ranked players to bring spectators, income and interest around the event.
A good compromise might be that of limiting the maximum of lower tier events you can play in a year based on your year-end ranking.
For instance, a player who finished top 10 in a given year, should not be able to play more than 20 events the next year, limiting the impact on the other lower ranked players (there is a rule that already limits the number of MM they can play, but not the overall number when you include premiere 470). Just think about it: a top 10 player who plays small events gets the highest seeding, a r1 bye, a lot of free money and basically takes the chance away from other player to earn something. This has happened multiple times (this year with Bertens playing 26 events despite being always ranked top10 and even top 5 at some point) but is ultimately unfair if we look at it in a "socialist" way.
Another possible remedy would be that of allowing players ranked higher than the tournament field level to play as much as they want, but automatically giving up their seeding and possible r1 bye; as an example, if itf100 is open to players ranked 60-110, the n. 59 ranked player could still play, but as a non-seeded player; Similiarly, should top 10 ranked players decide to play an MM, they would enter as not seeded and would not get the R1byes.
As you can see, there are many options, but each one of them has flaws and possible negative outcomes; even just limiting the prize money(let's say a top 10 player plays a WTA international, they only get half of the prize money) would probably have a deep impact on the whole system.