If you ever give it another chance, something they don’t really mention how important it is in the early game is that Morte resists 90% of all physical attacks. If you make him your main hitting people/in the thick of it combat person despite The Nameless One being the one looking like a hulking brute it will make much of the early game’s combat waaaaaaaaay easier and faster. The Nameless One himself is way more effective with using magic.
I never really found the combat bad though, it’s not like a huge step down from Baldur’s Gate or whatever, This always felt kind weird to me how today the consensus is that the game should have much less/no combat just because it has a lot of story. But not even towns being 100% safe in RPGs isn’t anything new in ones that want to establish a sense of danger. They do a good job in Planescape of making each party member very weird by D&D standards too which I appreciated (moreso than the actual Planescape source book did by default). Like it’s a D&D game where the main character can never use a sword or wear armor. 
We remember stuff like Fallout but for every Fallout or Planescape there’s ten Lionheart: Legacy of the Crusaders. Planescape was seen as a groundbreaking evolution of these at the time (and its combat had a lot of quality of life improvements, believe it or not, with how its menus worked if you didn’t want to do it in full real time) but it also came out in the midst of the peak of the “2D graphics = bad and old and lame” mindset both popularly and on plenty of game magazines and review website. So we never really got a game really of its kind of to follow up on it until Tides of Numenera came out (though I’ve heard that one’s writing is a bit of a step down, haven’t played it yet).
I don’t think it’s a huge fault that the game is a genre game despite the bigger emphasis on the narrative and the more zoomed in perspective compared to other overhead CRPGs coming out at the time. I think they did a good job building a game that works as a conversation with the game engine and type of RPG it was built out of. It’s great because of what it wrings out of that type of game.
There’s a few reasons you don’t see Planescape emulated as often though is because of budget realities and everything having to be fully voiced today. The only game that kinda tried to build on it was Alpha Protocol, but THAT game’s combat makes Planescape feel like Bayonetta.
There’s also its graphics and it being an RPG at all though. Planescape’s perspective is a little more zoomed in than other infinity engine games to better show off its pre-rendered backgrounds and make everything feel more personal, but those little things it accomplishes visually to move its type of game forward got eclipsed pretty fast. If you weren’t already into CRPGs, this was a CRPG that came out a few months after Quake III Arena, Unreal Tournament, and System Shock 2. Planescape’s graphics were praised at the time, but it was still 2D. I think on today’s hardware, depending on how one is playing is can be hard to see how it really does have significantly more detailed graphics than any of the previous games of its ilk.
It’s a small thing today but even it having real time shadows was like a, this should be pointed out on the back of the box kind of thing for Interplay’s games around that time like it and Septerra Core.
I would also say there was some fatigue for its type of game by the time it came out. You can see a lot of reviews of the time open up with this sort of yet another incredibly plotted RPG from Tim Cain/Bioware/Black Isle produced Infinity Engine RPG. There’s a language in them along the lines of like, no really, this game’s actually worth playing even if you played all the others.
So even if one doesn’t like the combat, I think a lot of the other little technical touches that make the game greater than the sum of its parts go unnoticed or were otherwise more quickly eclipsed, so it’s hard to process and make a legacy follow up game to something where the only thing people would ask of such a thing today is “make the story amazing and the characters really weird by 90s CRPG standards.” That’s about as general as you can get.