I could be a positive thing for many players yes, but at the same time this change would hinder their other development steps. They are in EA because thes want to find bugs and fix them(even if this takes ages sometimes) as well as implementing new stuff. But if they now start fragmenting their solid playerbase into 500 different mods and costom servers they would loose thousands of hours of free playtesting and the core development would slow down because bugs get caught way slower compared with now. And yes, you can download mods now too but it is way more effort to go to an external site, download it into the right folder and update it again and again so many people will just stay with the unmodded game because it is easier.I agree with you.
You are not telling add "...." content which is cool to see(and should be added later), but not important as few basic things.
You are not tellin "add my nexus mod to vanillia" either. Which is good, because TWs sources need to be spent in more modding capacities in limited time.
So, yes. The things u pointed are part of important stuff, and they should add them till end of year.
For TW the best path would be to just go on with development, improve the envoirement for modders(which thes seem to do faster when we look at all the responses from Dejan and others) and offer the things you want at full release as a kind of additional thing that boosts especialy the involvement of longtime players who have played the game in development and would not come back just because you say your game is finished now. This way when they release the steam workshop there is a larger amount of mods ready to go that can spark more interest at the same timewhen they plan a last large marketing push for the final game.