Might and Magic .

[Tweed]

I'd like to be a dick and say MM6, but Darkside of Xeen had the best and most unique design. In particular the Voweless Knights still look amazing. And the cloud dragons are sexy.
MM6 does have a nice style though, a special kind of jank the later ones just don't have.

 

[Fowyr]

MM got released in '86, MM2 in '88 (prettier Amiga port was released in '90).
Infocom was still publishing their adventures in second half of 80s, and they were not considered relic of the past.

Yep, I know, I played them. Still, most of adventure games were already graphic. Uninvited (1986), for example.

There was a lot of graphical adventures, but they were mostly drawing static screens to preserve memory, like Hobbit or Erik the Viking.

So they were not text adventures. Simple as that.

Maniac Mansion (1987) and Zack McCracken (1988) were progenitors of point'n' click adventures, removing the need for complicated input parsers.

I think that VGA standard was published then, but the games that used it were made some time later.
Amiga 500 was introduced in 1987, but it wouldn't sale well until 1989.

The point is moot, because EGA Might and Magic 2 was still very cute.

But still, first two MMs were published in time when playing text advenutres was not niche, computer magazines were full of maps and walkthroughs for text adventures.

Only it's irrelevant to graphic in RPGs. These magazines were full of maps and walkthroughs for RPGs as well. Average modern braindead player could not even draw a map of Wizardry's first floor, so it should signify something too.