I mean, if you play 1.6 version of these maps and compare it to todays versions you will notice some major changes. For example in nuke, timings are different (timing of arriving to a site as CT or T), textures are darker and it's harder to see opponents, there are extra tunnels near ct spawn, railings are different on heaven, A site is different, B site is different, and this list goes on. But looking at 1.6 maps, everything looks oversized. Crates are too big and the overall scale feels weird. I'm coming frım 1.6 and i was making maps for 1.6 too but i can say most default maps were not optimized for competitive play. CS:GO is certainly better at this. Also, nuke is a vertical map, meaning there are at least 2 vertical levels in the map that separates bombsites. These vertical maps are rarely a success. It's really hard to balance vertical maps because you have to factor in height and length at the same time. When you design a generic map, mostly you will adjust the length of the roads to adjust the timing, but in his case you have to think about height too. Remember, if you're above the enemy you have an advantage over him. (Similar to heaven in cache) and this can create unbalanced situations if you don't design it properly. I'm writing on phone so i can't fully explain right now but i tried to summarize.