Which sucks. I can't count the amount of times I've plugged in my iPad to charge and forgotten to check if the wall socket is switched on. On my android phone on the other hand I've never had this problem because there is an led which tells me if it's charging or not

Yeah, the difference there is that you have to crack open your laptop or power it on to know if it's charging if there's no light. iPad? Press a button. Now you know if you're good or not.

Audio feedback isn't too useful either

The charging light was a good innovation back when Apple introduced it. The rationale for having it there hasn't changed. Removing it was a clear regression.