Ah, with all due respect, but they do reflect that. If you will allow me to fill out your example?
First off, and from a design perspective, there is a big difference here between the Light armor and Soft Targets when a T55 fires. In these cases the AP value can be used versus the Light armor (the M-113 and the Bradley you mention, for those who might not realize, are of this target class). That means 3 AP dice may be used to fire from the T55 instead of its 2 HE dice (why would I use 2 when I can use 3, would be my question to myself). And if the range is 5 or less, that is 3 dice to make 5 or higher for a hit (accounting for the Point Blank Range modifier), rather than 6. Thats decent firepower for this task: three dice coming from ANYONE is scary.
Second: What makes it work in this situation - to my mind, and the choice I made - is the defensive side of things. Its not so much that the T55 lacks firepower, so much as the M-113 and Bradley lack armor,. THATS what should make them terrified (or at least cautious). Light armor are just that, Light, they only ever get one die in defense (barring terrain, concealment etc). But on average, and in the open, they should in fact be terrified. Three dice coming at them can probably make one hit (I err on the side of caution, but we both know how that goes) and their response will likely be nil in terms of armor defense, so yes they will be hit.
Third: we get to see how different weapon platoons are characterized: the M-113 has no capability to respond to a T55 (not even assault: it has no AP weapons and so is disqualified from assaulting the T55s). So again, on its own, it should be terrified.
The Bradley however has anti-tank capability, and might consider engaging the T55 for a short time before withdrawing (if it can). Well I would... ;-)