You have to remember that at the time, that there were really 3 game media back then. A) board games like DnD, B) the 8-bit Nintendo/Gameboy and C) the PC.
The Nintendo was cool and fast paced and was great to play with your friends, but the PC had all the adventure games. Pool of Radiance, Curse of the Azure Bonds, Bard's Tale II, Zork, etc.
PC Adventure games were all MUCH more involved that today's stuff. All the DnD games had decoder wheels and 500 page journals. You were expected to play it slow, read the journal entries, and immerse youself in the game. The closest thing I can think of today that comes close is Skyrim.
Most PC games today are built for kids with ADHD that aren't going to sit down long enough to use a decoder wheel. Heck, how many people actually read the quest text in world of warcraft?
Ultima IV actually had pretty good graphics for the time. The UI layout was really great. Most of the other games of the time were based on the old "wolfenstein maze" view of a game. Having an top down map was quite innovative.
There was a lot of 'searching' in Ultima IV. You had to find party members, you had to find secret doors. You had to find hidden items.
You had to run around do /say job, /say name, /say health, /say quest.. to every npc in the game to see if they'd tell you something.
Anyway loved the game, but it was built for a different time.