What's kind of sad is that the boss fights are actually so close to being interesting.. I found Jaron's fight in particular very atmospheric, although stupidly tough if you make one bad decision earlier in the game. It actually had me shooting at anything that moved at one point. However, the main problem is that all the bosses (except the last one, which I'd only tenuously call a boss fight at all and is actually the best of the bunch to the extent that sections of it reward stealth and hacking ability) are far too mobile and aggressive considering how brutal and quick most of the combat in Human Revolution is.
Also, although I'd hesitate to call it anything but an accident, having the right stealth augmentations does make the latter two fights a lot easier. Mark and track, anyone?
However, we really don't know the full story. It may be that originally Jensen was meant to be a lot more resilient and that even non-combat characters would be able to run around exchanging fire with these man-tanks much more freely. That could have been fun, and wouldn't necessarily have even been terribly frustrating, unless you wanted a non-lethal approach to every fight. But the way it was set up, the Tyrants did kind of need to die.
Speaking of them as a story element, they also needed to be much better integrated and explained in the game so we knew who the fuck they were. They do actually have interesting backstories (Jaron in particular), and for fuck's sake Gunther Hermann was one, merely knowing that would have given them a lot more context within the franchise as a whole. But all of these things only appear in a background novel, why the hell isn't it in the game itself? I understand a blacks ops unit is meant to be secret, but part of playing a Deus Ex game is meant to be uncovering secrets like that. This in particular is where the passing the buck to the guy who did the tech falls down, the failure to integrate them with the wider concept and story was what made the boss fights feel tacked on and unnecessary, and that was definitely Eidos' responsibility.