A real criminal who gets robbed, if they can't rob you back, would hunt you down and murder you. If you're going to argue the point that the game is called "crime city", you should also argue that in the spirit of crime, no action would/should go unpunished. That includes robberies.
But you can punish them, by attacking them back - you earn respect points, crap items (sometimes Boxes) and cash if they haven't banked...I think what you mean to say is that the retribution is not worth the effort....and yes, it's a shame you can't murder other players in game...agree! Perhaps some form of "retaliation cool-off" could be put in place at some future point to realign the game, i.e. after being robbed or attacked you can retaliate if you're strong enough i.e. break legs, knee groin, scratch eyes, break rib for instance and that reduces their attack stat by 20/40/60/80% against you only for 24hrs - would stop them from hitting you again for a while and is a little more real life..."Put Joey outta commission boys...he'll learn not to come round here again!"

Also, in real crime, the richest gangsters can buy protection. Can't do that in this game. The simple fact that "this is a crime game" doesn't excuse some of the "unfair" mechanics in place.
Yes, true, but buying a shield in this game would be pointless, and you can't buy protection in real life from rival gangs - police, yes, other gangs, nope (cease fire, maybe - whole 'nother kettle of fish) - this requirement is negated by proper hood management - If you don't collect from your hood, you will get robbed - simple.

Everyone has it in their head now to sit on a low level and try to max stats - therefore, no one wants to do anything that earns them EXP unless there is a big gain. The game was designed around level progression, not camping. This is why the EB event is so skewed, it's too easy for a low level with 10mil stats to complete, yet too hard for mid levels with 10mil stats.

To your question of whether or not it feels any different being robbed by someone with $10k IPH vs $10m IPH, there is absolutely a difference!....
That was rhetorical, but thanks for your thoughts on it.