While the Ultima series is ultimately a thesis on morality.
ONE GAME in the Ultima series qualifies as that. I, II, and III have such simplistic plots that they make Final Fantasy I look like Shakespeare, while the Eight Virtues became a secondary background element in V, and never were even minimally-important after that. Still, the plots in V, VI, and VII were pretty decent. Were they particularly complex by the standards of their day? Let's compare.
Ultima V: Warriors of Destiny (1988)
The virtues have been corrupted to serve the whims of a tyrant. You must rescue the rightful king and destroy the minions of the usurper.
Let's grab two other PC games from that year for a baseline.
The Bard's Tale III: Thief of Fate
An evil wizard defeated in the previous game has summoned another wizard. Kill him.
Might & Magic II: Gates to Another World
You are wandering adventurers. Eventually, you realize that your world is a spaceship, and an evil person is trying to fly it into the sun. Kill him.
Now, we'll compare three console games from 1988
Final Fantasy II:
Using a superweapon and evil magic, the EMPEROR has nearly conquered the world. Linking up with the last remnants of the rebellion, you must kill him.
Ys I:
Locate the books of a ancient civilization in the hopes of stopping a rising evil. This will take until Ys II or III.
Dragon Quest III:
An evil witch is threatening the land. You must wander the earth collecting the artifacts you need to get to her to kill her.
From this, we can conclude that Ultima V is, plotwise a step above the average RPG of the era (with the caveat that I'm only looking at games that eventually got an english release, as I can't understand the summaries of the non-English ones easily.) In terms of combat mechanics, all the games except for U5 and YS use essentially the same "line-up-and-hit-em" mechanic, with roughly the same tactical options (although the console games tend to be more transparent about things, with spells listed in text instead of having to be looked up in the manual, and much more coherent character screens.) In all cases, not being able to defeat an encounter generally means you don't have enough levels or good enough equipment, although bad tactics can play a part as well. Ultima V's combat, despite being the most tactical on the face of it, is actually quite bad, with mostly-pointless spells, positioning being barely important, and enemies barely worth the trouble. Ys is the worst here, being mostly "bump into the other guy".
In terms of character development, YS is the worst, with U5 in second, with very few levels, no real customization options, mostly worthless spells, and one bit of easily obtained equipment rendering everything else pointless. BT3, MM2, and DWIII are roughly the same here, with simple level advancement allowing you to hit harder, cast more and better spells, and take more damage, while a steady stream of equipment upgrades improve your ability. FF2 is the odd duck here with everything increasing with usage, theoretically allowing extremely precise customization, though the very buggy system means this rarely works.
In terms of world (not exploration), YS is at the bottom, Ultima V is at the top. FF2 is in second place with DWII, and the rest are tied for third. Ys is simply too sparse, MMII and BT2 mostly have empty corridors with nothing but merchants and quest givers (and monsters), the second place holders have plenty of filler NPCs to populate things and dispense bits of info, with plenty of areas that seem dynamic, while U5 takes that illusion of life and motion and makes it a reality, aided greatly by the conversation system.
Finally, we turn to exploration. Ys has pretty much none. Ultima V is tops here, with exploring actually feeling like you're going through a world. MMII and BTIII have a great deal of exploration, but that's more a matter of methodically mapping every FUCK YOU, A TURNTABLE single square HA HA! INSTANT DEATH TRAP to make sure LOL! YOU HAVE NO MAGIC you've missed ROFL! TELEPORTED YOU TO AN IDENTICAL ROOM! nothing, constantly enduring sadistic crap just so you can get one clue or treasure that you need to proceed. FF2 and DWIII are straightforward on the world map, and the worst you have to deal with in dungeons are dead ends, out-of-power monsters, and the occasional damage floor that you have to go through.
Frankly, the only difference I see between console and PC RPGs is that the latter produced a few more gems, while the former generally lacks the not-so-subtle sadism that distinguishes the latter. You generally do have to take more notes in PC games, but that's as much a consequence of presentation as anything else. Your goal tends to be more straightforward, and is broken up into manageable steps, so the only way you're going to forget what's going on is to leave the game for a couple of weeks.
I would also like to clarify that the "childish" accusation tends to be more "Console games are made for children and thus are nothing more than "press the button to win" games with absolutley no depth. THey don't have any other option, because they don't have enough buttons."