I personally think DeFi will eventually rise to a point where it will basically be bank or any financial institution that poor people around the world in third world countries can take advantage of with the help of the rich people all around the world, and I don't mean rich like Bloomberg rich, I mean rich like you and me because many people in the world lives under 30 dollars a month now, DeFi is for them, not for us (at least not now).
If defi grows out to become a huge industry, I'm confident that the centralized finance industry will improve the quality of their service further and reduce the fees or in some cases offer free finance to those who really need it.
In fact, it's already happening; there are numerous countries already where you can wire money instantly and for free at any time of the day, even during holidays. I have seen those memes on Twitter where people make fun of banks being closed and that Bitcoin always works, well, banks are getting there as well. Innovation triggers more innovation. Bitcoin innovated the banking sector.
Ethereum's defi ecosystem would be even better if fees could be paid directly in stablecoins instead of Ether. I know there are certain workarounds with smart contracts, but it should be made easy for the common joes who just want to use the simplest form of money.