I’m obviously generalising, you can find small groups of people complaining about literally anything and everything. The general playerbase was not complaining about raid difficulty in TBC, especially because the way people looked at the game back then was completely different to today.
Back then people looked up on top raiders as like superheros or something, if you saw a full Black Temple geared player in Orgrimmar while the rest of the server was still pushing through mid T5 it was like you were looking at a celebrity, people felt damn proud of their T5 even when T6 was current.
It wasn’t really until the end of TBC with Sunwell that any sort of discussion like this started to really take place because it was clear it was designed for the RWF, and it was drastically more difficult than anything before, but even then most people were just happy they could save their dying guilds from poaching when the attunements were removed, since that was the real topic of discussion in TBC, attunements and guilds poaching making it impossible for guilds to progress because they always lost their best players to better guilds.