That's a good turn of my phrase, but you're wrong. By nature of unaggressive enemies combined with infinitely regenerating shields and health makes ME2's most optimal strategy at the highest difficulty hiding in the back with a Widow or Revenant. You can play differently to make things more challenging for yourself, but the game never forces you to leave cover aside from the single Pretorian fight. Even enemies with rocket launchers are countered by the god-like chest high walls. Playing a Vanguard makes it abundantly clear how imbalanced Insanity is.
When ME3 added Brutes, Phantoms, Banshees, Atlases, etc., they made the game dynamic by forcing you to move. You can see the problems present in ME2's combat when fighting the Geth in ME3 - they don't do anything other than take cover and hit hard. The proof of this exists in the multiplayer-only Geth enemy: the bomber drone. Literally all it does is force you to leave cover, and it makes the Geth infinitely more engaging to fight. Even the Collectors are done better in ME3 (MP) by the fact that they made the Pretorians way, way more aggressive and gave their beam the ability to pierce cover, as well as added Seeker Swarm enemies.
I will admit that ME2 giving each class their own distinct identity by way of unique abilities (charge, cloak, tech armor, etc) was a great addition to the series. But, as it is the first implementation, the iterations done to each class in 3 and Andromeda far outclass the originals in 2.
Not really, you can be very aggresive in ME2. With Vanguard in particular, cover becomes more like an accessory than the main way to play the game, even of Insanity which I'd say is perfect balanced. But yes, it's TPS with focus on cover, like Gears of War or Uncharted are, but I don't think you can use it as an argument against it.
And it's funny that you mentioned rockets, because in ME2 is very easy to dodge them outside cover.