The difference would be our path over the last 5-10 years. Qualifying gets you a financial boost, and one that is then taken away from one of your direct league rivals. That gives you the opportunity to build on that do repeat the performance the next season.
If Leicester gets in, gets the money, but all the other 6 funding teams on the PL still gets it, and gets it every year, building that over time gets increasingly difficult.
Keeping the best players will become more difficult. Financially, but also in terms of the competition.
This depends somewhat on how well teams have to do to get in. But assuming 5 teams qualify from all of Europe each year getting in as a qualifyer will be difficult, doing it repeatedly will probably be harder than successive top four finishes is now. And 6 of your competitors gets that financial benefit every year.
Wouldn't want to be the ones near the top, but left out.