@davids I think you’ve got that time period spot on. By 1998 the teams had got a handle on the dimensions of the cockpit safety devices so the cars started looking “correctly proportioned” again and post 2004 things got a little too crazy on the aero front.
As for 2004, there were so many good looking cars on the grid (just saying the BAR 006, the Jaguar R5, Sauber C23, Ferrari F2004, the McLaren MP4-19 and the Jordan EJ14 gives you half the field!), it is such a pity that we all remember 2004 as the season where we all got bored because Ferrari kept on destroying the field!