If you want to make something like Zelda replayable, the trick is not to design complete dungeons of any size at all. Instead you design rooms themed to a type of dungeon. Lots and lots and lots of rooms. Then you come up with a clever way to have a number of different map layouts for each dungeon type, and then you fill those map layouts with random types of rooms, with some specific parts of those maps having specific types of rooms. A more structured form of randomization compared to Binding of Isaac, but a similar idea.
Say you have a fire themed dungeon and a tower themed dungeon. You just need a bunch of different map layouts (linking rooms together) for each, and then a bunch of different rooms of each room type - combat rooms, escape rooms, trap rooms, puzzle/key rooms, chest rooms, mini boss room, boss room, etc. Each map layout would define what types of rooms each room could possibly be, and you randomize the contents that way.
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