In the TBC ones you had to do what you did, only to survive, not to just breeze through. There were places that were hard to run without a hunter / mage because some trashpacks needed proper chain CCing.
Also, the people that entered those heroics, really grinded the rep to be allowed to run them and knew the normal versions by heart. And for every group of heroic you had to grind the rep of the associated faction to be able to get the key.

Its not that players got better, in the contrary: players got lazier due to the "nerf" of HCs and the LFGtool. Blizz needed to make them easier due to that tool, otherwise no PUG would survive. In TBC I spent ages waiting for groups in tradechannel and then got invited to those of which people knew me and knew what I could do.

I like the LFGTool though, because it reduced the waittime for DPS tremendously. The casualization (is that a word?) of HCs (and thus the lack of need to really know how to get 95% or more out of you char only to live through one) is just a result of it.