People suggesting very high fees are just in desperation mode, trying to cut down their competition 
Developers with money want to cut out the little joe hobby, making easier to sell more for less marketing costs since there won’t be so many apps in the store to fight against, for consumer attention.
Steam has never been a “holy graal” of games, this pseudo elitism towards Steam posed as a high standard storefront are just commercial interests speaking; since the early days there’s crappy shovelware selling over there.
If you don’t want to deal with flooded marketplaces, go sell on platforms hobbyists have no free access to; suggesting to keep them out of Steam will simply make Valve decrease anual revenue instead of helping Steam to grow, they will never do that, wait and see.
Valve’s interest is simple: QA costs time and money, they want to remove quality assurance from their expenses list.
They usually make their consumers work for them while they keep the money, this is why Greenlight exists today; but developers cannot accept the fact Steam is becoming Google Play store for PC and have always complained about it.
They tried the same with paid Mods, but backlashed and they gave up for now, but they will always try to make someone else do their work for them while receiving money for it too.
What is actually going to happen is nothing will change:
- There will be trash games published, because some people actually buy those bad games.
- Only the big releases will get store front page on the bigger banners.
- The flood will keep on flowing, small games forgotten quickly.
- The bigger games will keep selling millions as usual, nothing changes.
I just feel a little sorry for those who gonna pay for this fee, no matter how small/large it end up to be 