Welcome to the real TBC. TBC classic is just a toned down version.
Dungeons need to take a diffrent approach than WOTLK TACTIC TANK GOES LEROY JENKINS AND REST JUST AOE.. THe require a diffrent approach which is you need to use CC, stuns, slows, snares, all that kind of stuff.
Well if you are giving up and complain at forums just after one hellfire ramparts normal, then you definitely should just wait for wotlk. Well normal dungeons get a bit easier once you get that gear and normal dungon gear from high level tbc dungeons like shattered halls or shadow labirynth is enough to go to raids and unironically t4 raids are quite easy. Karahzan attument is done by doing normal mode dungeons.
The real deal are heroics, where you need a specific comp to get through some heroics. And wait, there is more. You will have to do some heroics in order to get attunments for T5 SSC is quite easy because you just need to reach questgiver at SP hero (SP hero is considered as one of easiest heroics), get quest, get items from nightbane and grull, and you have attu to SSC. And there is the EYE, if you think Hellfire ramparts normal is hard then you didnt experienced the real hard. What we have here, doing shattered halls hero but with time limit, doing arca hero (Arca in normal mode is already hard) and making sure that npc you free during final boss ecounter wont die(getting here is the hard part, meanwhile final boss ecounter is quite easy because that NPC helps you a lot during fight), there is also SHadow Labirynth heroic (Murmur on HC will definitely test your party's knowledge about class abilities) and Steamvault heroics (Where getting through first boss is an RNG hell).