This is acutally question for "older" forum members.

So my question is did Bethesda ever add or changed [read fixed] something that players complained about on forums or they are just considering to that in their next game, or they fixed bugs and technical problems ?
Im asking for both TES and Fallout series..

Reason I am asking is just to find out is there any purpose of complaining and explaining their mistakes..

Highly doubtful that they will read your exact critic of the game, but they do read them. Thousands of people have expressed their opinions and it's impossible to keep track of everyones, but they should have the jist of what people ate complaining about. But don't think they'll make major changes to perks, skills etc in DLC, they won't.

Complaining has more worth than remaining silent... which is worthless.

Well, there was the Broken Steel DLC for Fallout 3.

They changed the game from having an ending to being able to continue playing after the ending.

Many changes to Oblivion, and now Skyrim, came from Bethesda listening to the fanbase. So yes, it is worth posting complaints when done in a mature and rational manner.

The level scaling in Oblivion. people complained but Bethesda didn't fix it, they let mods like OOO to take care of the problem. Next time they changed the system, so they silently admitted the old system was wrong. But they didn't fix it back then when the console players really needed.

I imagine they will pay more attention to things like published game reviews and the statistics gathered about people's play-styles from the data collected through Steam rather than complaints on the forums.

People's complaints are often contradictory, as different people will want completely opposite things and they can't please everyone.

Unlikely they will rebalance the game to your exact specifications, which is what so many people demand. They did, however, fix level scaling to a large degree btw Ob and Skyrim, so good, constructive criticism is indeed noticed.

More people need to give good, constructive criticism about the loss of spellcrafting, which was an excellent activity, and the loss of which has really taken something away from the game, IMO.

When Todd thinks something is redundant, I'm not sure what can I say to convince him the loss of spellmaking is unfortunate. I'm sure he already thought this through countless times, like he did with attributes, spears, levitation or whatever. If I was in charge I'd bring them all back and find a way to make them work better.

Yes, i think they probably look at mods though, they look at popular mods out there, and decide what to add in the next game. Like in oblivion there was a mod to remove the flowers when you picked them; that got through in skyrim.
And uhhh since complaints lead to some mods, >> link?

They fixed the journal in Morrowind. They say they are working on correcting some balancing issues in Skyrim. Complain away.

If you don't complain then nothing will be changed. So it is always best to give Bethesda a idea of what they are doing wrong.