Well, that, in my understanding was the original intend of insurances, bounties and fees: To get you to do other things to build up the finances to recover from the financial punishment.
However, as earning money for seasoned players is no challenge, all financial punishment is no longer of significant concern for them.
Hence, some different kind of temporary sanction is needed.
Your reasoning is flawed.
You're correct to say that the intention of insurance is to encourae a player into performing activities in order to avoid a loss of progress; however the point is that pretty much all activities result in the player earning credits to some degree or other, so there is no restriction on gameplay of any kind imposed by that requirement.
The purpose of fines and bounties is to impose a penalty for transgressions. That penalty takes the form of depriving a player of some of his credits; the penalty is effectively the opportunity cost of whatever else he could have done with them. It doesn't restrict his choice of gameplay activity in any way and it never did because again, if a player wanted to earn credits to pay off a bounty or fine pretty much any gameplay activity would allow him to do that.
The biggest point you're missing though is that any of the above allow a player to earn the credits
first. Then if he does incur a fine or a bounty, or blows his ship up and needs to make an insurance claim, he can pay it using credits that he earned doing what he wanted to do. Replacing the ability to resolve those issues with previously earned income and instead forcing a player into a form of gaming purgatory where he is forced to perform a particular task, or forced to do nothing, until his period of incarceration has ended isn't remotely the same because it does restrict gameplay choices.
If your argument is simply that this is how it should be, that the punishment for transgressions in-game should be to prevent a player from actively playing the aspect of it that he wishes to, I can't see how it would be considered to be a benefit by anyone other than the most ardent role-player.
As I already mentioned I have no problem with the concept of fines and bounties having more meaning in terms of how they affect a player's game experience, in fact I think it's necessary really because they have as much significance as a parking ticket issued by a dodgy wheel-clamping company right now. I don't see this as being anything like a sensible way to go about it though.