Well, I'm not going to tell people what they should and shouldn't find appealing. I think JJ and Jeff's graphics are horrible, but if folks see something in those visuals that really registers with them, I think that's great. But I also don't think that saying JJ and Jeff looked good for its time is an indisputable statement.
People apparently love the "huge" characters, but freakin' China Warrior was out at that time. CW is a much better example of a game that was in its own class at the time as far as character size was concerned.
People also say JJ&J represented a significant step forward from 8-bit times. I'd sooner point to Victory Run, which was also out at that time and which demolished 8-bit driving games visually to a much greater extent than JJ&J beat out the NES platformers. (In fact, I think a lot of NES platformers look better than JJ&J.)
And it was, what, three or fourth months later that R-Type hit the PC Engine? Anyone who thinks JJ&J even comes close to R-Type visually is INSANE. After three or four months, JJ&J's graphics were already obsolete.