I lost a few jobs already to mostly Chinese studios.
The whole “studio” outputs 10 times faster than I could and costs 10 times less.
And unfortunately they often have a good quality too.
It’s not always messy geometry, duplicated vertices or wasteful UV layouts, so you can’t blame clients.
I’d like to see some “fair-trade” assets though, without middleman, sieving off the money, leaving crumbs for the artists.
In the end it would be beneficial for the people working there, and in the long term, level the payment between the two extremes. But this will be decades…
However I think those prefabs are nice. There are many people with good ideas for games but with neither artistic talent, nor the financial power to create state of the art assets. And the best game isn’t usually received well if the graphics don’t have a certain quality, or that retro-charme “abused” to sell games lately 
A lot of games for instance in the Linux landscape are good, but never made it out of the dark until some artist contributed a decent graphics pack…
So this is a way for someone with a vision to realize his dream rather easy, have a better chance for success and as a result found a gamestudio at one point and hire artists for a graphics department to tailor assets for the game and develop an own style.
That’s at least what I want to believe 