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.
Of course it does :) The two games are decades apart and 1800 was known to require quite a beefy PC to run good when it came out.
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.
(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!!)