The cut being lowered will also lower features on the consumer side and then sales. An higher margin on Steam for developers will also increase the amount of game released on the platform and the issue would stay the same.
Because at the end of the day, this cut debate grew because more games were being released and the average revenue from being on Steam lowered (since more games means that consumer will buy even more different things). If the cut is being lowered to say 20% just because devs feels like 30% is too much, in a couple of years we'll see the same arguments and now devs would want a 10% cut and so on.
What's needs to be done is to find the equilibrium for a sustainable cut which allows devs to more easily break even while allowing Steam to invest in their platform and in maintenance. Because rest assured that a barebone client (especially if it's curated like EGS) will never reach the userbase Steam currently has.
That's not true,this is like saying if you lower a 20% tax to 10%,people will ask for it to be 5% in the following years etc... it's just a faulty argument. There's always a golden number and every industry should always strive to bring the balance in favor of the primary sector. This way more people/companies have the motives to invest to create a product rather than be the middleman who sells it.
As far as Steam goes, there's profit for shareholders that doesn't necessary translate into investing in the company,so it's not necessary that lower Steam income will translate into equilevant downgrade in features.
I'm not pro or anti EGS,but I'm sure that their client will evolve over time,as Steam's client did over the years. I'm sure it won't be just a barebones service that just has a low cut. They just wanna hit a big revenue in terms of money,that's what they are aiming for,but since the game industry has grown substantially over the years,they can get A LOT of money with half the percentage of Steam and still offer a great service.
Bottom line is that EGS is not the saviour that has come to save us ,but I'm sure the industry,especially the digital retailers, can be super viable with a lower cut than 30%. If you look at the financial reports of Valve,you'll understand that as great service as Steam is,there's no way it needs THAT much money to be sustained. It's just shareholders enjoying their good profit,but the amount of profit can always change and still be profitable