Legacy of the Wizard (...) had one flaw, and that is the fact that the game is not linear.
Try saying that about Metroid!
"Lemme tell you, Metroid may be a pretty good alternative to Probotector, only problem is the game isn't straightforward at all."
Or could it be that for some twisted reason you accept Metroid as your patron saint, but lay blame on LotW?
About the map
This game doesn't need one. Every room has its own look and they all are easily recognisable. As you traverse the dungeon you should be able to make a mental map, although I suppose to do that one cannot be the type who would write a shopping list for as little as a dozen items.
The underground world is about perfectly square, within there are the character-specific sub-segments, which take up big chunks of the whole (about a fifth each); those sub-segments are rectangular and are indeed mostly linear parcours, hardly convoluted stuff.
One segment is hidden due to its entrance being obscured. If you made a halfway accurate mental map, you will know which walls are its outline.
Even Metroid has bigger problems because of its primitive copy/paste nature. Brinstar's shafts are distinguishable only by colour and the other zones have several examples of reused corridors. It takes tenfold the effort to memorise Metroid's world.
The other points made are even more uninteresting and reek of modern game-design mentality. Lucky you there is a rapidly emitting faucet of lame-ass modern games.
I feel as if Legacy of the Wizard was designed by Satan himself.
I'm sure many NES-players had similar views back then, and hundreds of 'Mericans (no PAL version) whined to Nintendo Hotline counselors.
"This fu##in sucks, I dunno what to do in dis game. Lemme talk to the game designer! He must be Albert Speer or something! Is he trying to build Hitlerhausen here?! Either a Nazi or a lunatic or even Satan comitted this hideous crime. Make it so this doesn't happen again, your shitty game is broken! And send an exorcist to the goddamn development facilities!"
Developers overestimated the intellect of their customers, and games became dumber with every generation since.