I definitely wouldn't recommend skipping Ultima 9, myself. It does have its rough parts--for myself, I'm not a fan of the plot, and it very much has some issues with bugs. However, it also has its charms, I feel--again for myself, I find its implementation of an "open world" to be excellent.
Whatever you come to think of it, I feel that it's worth giving it a try, at least.
(Ultima 8 likewise has its issues and its charms, although it's perhaps a less-divisive entry in the series.)
I do plan to play 8 and 9. For me it's at a minimum a historical learning experience. Ultima has had a big impact on me as it was my introduction to RPGs, but while I played 1 - 6 back in the 80s/90s, I never made it past 6 and in recent months finally committed to playing the rest of the series that I missed. It's been really fascinating to see the changes from one game to the next.
I've heard about the issues with 8 and 9 for years and I actually look forward to experiencing them first hand to get better feel for the games evolution. That said, if I find them interesting but not fun I won't hesitate to use a walk through or even stop short so as to not prolong the experience :-)
This would explain why Nox Archaist has so much in common with earlier Ultimas (particularly 5), as opposed to other CRPGs of that era. (With that said, the area-based progression of enemy strength, and the growth of skills through usage, are very not like classic Ultima.)
Other CRPGs that I'd recommmend looking into for historical reasons, if you haven't already played them, are:
* Wizardry 1-5 (Wizardry 4, in particular, is a one-of-a-kind game, as I don't know of any other game like it)
* Might and Magic 1-5
* Bard's Tale 1-3
* Perhaps the original Dragon Quest (which is very different from modern JRPGs despite being the game that spawned that sub-genre)
I've been thinking of making an RPG myself, though the influences will be different; it's looking like maybe SaGa, Final Fantasy 5 (that entry in particular, with maybe some FF2 influence), and perhaps Wizardy/Bard's Tale, as those games are what I grew up with (albeit only the Game Boy SaGas, and I only played FF2 and FF5 after fan translations came out), and those are the RPGs I generally like the most.
By the way, there's apparently a game coming out for the Apple 2 called Lawless Legends, and there's apparently a demo available; you might be interested in that.