In theory, Hyperion is fine. What really hurt it enough to be useless was fleet bloat in the 0.9a releases. Fights grew bigger and bigger with successive releases since 0.7a or 0.8a, but PPT has remained mostly the same since the 0.6.x days. Also, skills were weakened by 0.8a. By the time Hyperion can kill a cruiser, its PPT is gone and it needs to retreat. Might as well bring an Afflictor or Harbinger to do the same work or more in less time. Afflictor is cheaper. Harbinger can hang around and pick off small ships for a while longer. It also did not help that the tweaks to attack phase ships while phased also work against Hyperion and the phase skimmer ships.
Also, objectives used to be important, but now they can be ignored. Hyperion was great for grabbing objectives long before anything else, but that role is now obsolete. (That said, I really dislike objectives. They can disappear and there would be much rejoicing from me.)
If I want to pay 15 DP for a ship, I rather use Falcon over Hyperion in the modern releases. Falcon has range and much more PPT. Anything Hyperion can do, Afflictor can do it cheaper.
Basically, Hyperion itself did not change much if at all, but the rest of the game did, and fleets have more hp thanks to more and/or bigger ships.
Hyperion may regain its usefulness if endgame fights become smaller like they used to be, or PPT raised across the board to account for bigger fights.