Is there a point to collecting as many cyber-hearts as possible?
you can only hold 99 hearts, and when you get the skill for auto-loot on takedown, this number will be reached very quickly (if you do a lot of takedowns of course). You'll probably only use maybe 25 hearts throughout the whole game, though. I would still continue to loot cyber soldiers (just not obsessively), because they do give money.
Cyberhearts are only useful for luring blood-dragons. You rarely need to do that, and when you do, you only need a few of them.
But notice that looting enemies does not just give you cyber hearts, it also gives you some credits.