Here are my actual thoughts in the interest of keeping the first post clean:
I think this is a good idea, though there will be growing pains and resistance. Having the option to give the author money, especially for mods that one considers essential to the enjoyment of the game, is great. I can see myself uploading to both Nexus (as a free alternative) and the Workshop (for those who want to offer monetary support).
In terms of pricing, I expect the market to self regulate. We're probably going to see some really expensive and really cheap mods at first. There will be modders who think their work is worth exuberant prices, and there might be users willing to pay those prices... but, in the end, much like the indie or mobile game scene, things will likely depreciate back down to reasonable (or even too cheap) amounts. We've had free mods for over a decade - no one is suddenly going to want to pay for every last thing.
I also think that they are releasing this at such an awkward time to give them (and the market) time to figure things out prior to the release of whatever they have in the pipeline. Their next game (whether it is FO or TES or something else) will doubtlessly use this system, and having time prior to launch to figure everything out is invaluable.
This would be my absolute dream scenario. Had mods been monetizable back in 2009, I probably would have kept up with modding.