This was part of the reason why a lot of previously nationalised stuff was privatised in the first place. MP's would get people complaining to them about the quality of their phone lines from BT for example.

It all moves in cycles, I could well imagine the same situation happening again in 20 years.

The timeframe for changes is so long that this has zero chances of affecting any politician's career

Yes, but they're still judged for their actions, so they'll lose voters if they do nothing or take actions that will be widely criticised by the press.