Spren should be free to choose who they want to bond to. Is it a world of amazing technology, if the system is based on slavery of a population. With freedom will come even better technology. Instead of fabrials, we will have Knights Radiants!! Think of the glory!!
Spren can't choose. It takes a measure of intelligence to make a true choice. Except for a few unconfirmed cases, no spren has ever displayed the intelligence of an axehound, a chull, nor even a chicken!
Spren are only ever seen near the things they are attracted to or responsible for (depending on one's position in that debate). Let's say, for the sake of argument, that spren
do possess some type of sentience, or even sapience. Who is to say spren
aren't free to choose who or what they bond to? If gems attract spren, then (as I have said before) the spren must benefit in some way.
I don't see any outcry over the "imprisonment" of Stormlight within fabriels or gems. After all, what merchant or moneylender would want anything to threaten the vital service they offer when recharging dun spheres.
Anyway, on the Greatshell debate, I have reason to believe (though to proof) that they may be related to Thunderclasts and voidbinding. If that is the case then we should not be afraid to cull them. Take Chull's for example. They seem docile, and we really on them for pulling great weights, but if suddenly some force was able to change them, make them hateful, then they would be deadly. Think of the parshmen/parshendi/voidbringer relation.
Innocent until proven guilty. It seems strange that a civilized and progressive man such as yourself would forget such a basic concept.