There are already games like Low Magic Age, such as the Gold Box games and Knights of the Chalice. The main difference is that the latter actually have fleshed out campaigns with handcrafted dungeons and encounters, plus some random encounters also thrown in, of course. Apart from that, they also had better implementations of their rulesets (no cooldowns, for example.)
There are lots of games that 1) use a D&D or D&D-like ruleset 2) have full-party control and creation, and 3) mostly consist of dungeon crawling. An example of this are Wizardry 1-5 and their Japanese clones (they use different iterations of a homebrew version of early D&D.)
The thing is, these kind of games do not usually procedurally generate their dungeon content, instead you get large amounts of handcrafted dungeon content, which IMO tends to be superior in design elegance and complexity (e.g. the way that areas are interconnected, trap and encounter placement, layout themes, challenge etc.) You should also not have a problem with running out of content (due to the quantity of dungeons) or replayability (due to the complexity of the combat, party-building, and dungeons.)
The only reason LMA relied so much on procedural generation is because, as you pointed out, it is little more than an engine. So if you are willing to forego this requirement, I would recommend:
-The Gold Box games, starting with Champions of Krynn, for a better interface than PoR.
-Knights of the Chalice.
-Wizardry 1 and Wizardry 5. The SNES and PS1 versions look good and have decent interfaces.
-Elminage Original, Elminage Gothic, Stranger of Sword City, and The Dark Spire are all recent Japanese Wiz-likes that are worthy successors to Wiz 1-5, if you want something more modern-looking. Note that Elminage Gothic is very punishing for beginners to this sort of game, so you might want to try one of the others first if you don't already have experience with Wiz-likes.
-Icewind Dale and TOEE have similar design to what we have been discussing, but in isometric form.