The Story of Super Mario Bros. 2 - YouTube
A long story cut short - Super Mario Brothers 2 (Japan) version was too hard for a Western audience. So they had to make a western version and a Japanese version. Shigeru Miyamoto - the founder of SMB2 was also the founder of Zelda. He (and a lot of other game developers) got the hint and changed Zelda's vision forever so it would be more accommodating for a western audience to whom they were trying to sell and make a profit from. And one part of that vision was the extremely easy difficulty - which is what you see now.
But prior to that vision change, Zelda was a difficult game. If you've ever played the NES version of Zelda 1 and Zelda 2, you'll see how different they are from the Zelda you're used to and I'll give you the ROMS and emulator via email if you want them. It's the Zelda that I fell in love with and the difficulty is just wonderful. I didn't like Miyamoto's design change to cut out the difficulty and I've stayed away from modern Zelda games because of it.
It's not about whiny losers and games being too easy. It's about profit. You see ultimately game creators who are paid to make games are accountable to their paying fanbase and if that paying fanbase tells them to nerf the difficulty then they pretty much have to listen to that in order for the game to sell and for them to make the most profit.
You must be referring to the wall panel in level 4 which can be walked through. It can be seen with the lens and I think there is the lens symbol in that room. Also if you have the compass, it sounds a beep in a room where there is an important item so you only have to kill all enemies in a room where there's a beep.