Can you elaborate a bit on why you think so?
Ultima 7 had shit combat and a shit inventory
Ultima 8 was an isometric action adventure with a filler plot
Ultima 9 was terrible in almost every regard
Absolutely fair. To me, however, bad combat can be a deal-breaker in some games, but not others. The rubric for this is pretty case by case and not in the least bit concrete, even to me.
For example, Planescape- Torment's combat is something I usually actively avoid, choosing any possible dialogue options that get me out of having to engage in it. In spite of this, I (and from what I've seen, the Codex's rankings here) consider it one of the best games of all time and an easy contender for best CRPG. A similar game, Icewind Dale, looks and plays the same, but trades incredible storytelling (Planescape's sctrength that allows me to overlook its lackluster combat) for a total combat focus. If that game, or even a game outside of the world of CRPGS (like character action games by Platinum Games, etc) had bad combat, I would dabsolutely write it off as a bad game as you do with Ultima VII. I've played about 40 hrs of The Black Gate so far, and while I do find the combat to be a big ball of nothing, I love the world, freedom, writing, humor, characters, interactive elements, sandbox-style experimentation, the magic, the quests, etc. These far outweigh the poor combat for me. So, I personally wouldn't say a game is bad simply because it doesn't have good combat, especially if there's so much more to and it has tons of other merits.That said, perhaps combat is one of the main reasons you play RPG's (as it is for many) and you find it can make or break a game. I totally get that. Different strokes.
As for the inventory, it's annoying sometimes, juggling every character's bags within bags etc. and the manual feeeding can be tedious and stop the flow of things, but I'm still cool with it so far. I haven't played Pagan, but I trust you on that because I've heard the same sentiment regarding it from most people. Ascension I played in middle school and, even then, before I developed "taste", I knew it was a clunker.
I've really enjoyed my time with U7 so far, though.