I would argue that anything that shows up with the degree of ubiquity that "Demolisher" does means there is something wrong. As it is so prevalent, so ubiquitous, that means there is probably something wrong the the pricing. And, because of it's power, people design lists specifcally around being able to answer that threat.
No one says "I have to take 'x' because I might see Instigator show up".
The ubiquity of Demolisher and the requirement for opponents to have an answer to it (and the fact that all competitive players design lists with it in mind) means there is a problem with it.
That's... some ropey reasoning. I would argue that the reason Demolisher shows up so much is because it is priced precisely correctly.
Demolisher is popular not because it's broken or unbalanced, but because it is always useful. Like Gunnery Teams, Electronic Countermeasures, X17 Turbolasers, Leading Shots, these things are all very common because on the ships that benefit from them, they're invariably beneficial in just about every game. It doesn't mean they're broken - it just means you'll never regret taking them.
Instigator doesn't require a countermeasure because it won't always be useful. Indeed, if you're not taking bombers, then you have nothing to fear from Instigator. The same goes for the other Gladiator title, Insidious - it's actually a fantastic upgrade, arguably worth a lot more than 3 points when you get to use it - but the occasions when you do get to use it, and where it makes a difference, are very few and far between.
It's why I always take an Imperial-class Star Destroyer. Not only do I love it (more than a friend), but there's never a moment when it isn't useful.
The other thing with Demolisher is that it's fun. It's a fun upgrade to have on a ship, and so people enjoy adding it to their fleet.
But ubiquity does not equal overpoweredness, or imbalance - I don't believe you are measurably getting more out of Demolisher than you would out of spending those ten points elsewhere. Indeed, you could instead take an extra TIE Bomber, which would likely be more useful in some fleets, or you could put an Intel Officer on the Gladiator instead, and increase your bid by three points - which I would argue is also a compelling alternative. But Demolisher is just more fun than either of those.
Edited by jhox