Hmm I feel this might just be nostalgia at play. I've not played any Anno games, but comparing the two side-by-side and 1800 looks leaps & bounds better to me. 1602 looks like it was drawn in MS Paint.
(A friend’s mum was famous among us kids because she could play 1602 well, I always got bankrupted by tools. How did she do it!!)
My point was 1602 holds up visually in a sense of doing it’s job assisting the game mechanics, something most modern games often fail and over complicate. Also.. nostalgia.