i dont think the problem is how small the map pool is, there is teams that hardly can play 6 maps out of 7, now imagine 9. At the same time it will make a bigger mappool and more maps to watch, it will reduce part of the skill on the maps since they would need to train more maps + rotate maps too often would reduce it aswell.
Aztec is also pretty hard to remake without changing the original vibes, maybe becoming a green cache 2.0, great map, good layout, but not really that much well accepted. But imo the biggest problem would be bring Tuscan back, as i already stated on other comments, i do believe this map doesn't suit CSGO that well, multiple corners to check, molotov mechanics, too much claustrophobic places, etc.
Imo new maps should be created instead of only working on doing the old ones, the metas had change a lot over the years. Anyway, i would like to see some "old" maps returning, but it would be purely the 2016-2017 version of cobble or a cache with some new updates. About Aztec, i feel like this map has big balance problems, maybe a rework for casual / scrimmage, but not competitive for the reasons i already said before in my comment, on the other hand, Ancient could take the place, it is similar to Aztec in graphics, if the map becomes more nice to play and the textures become more colorful, i would definitely play this map + i dont think it would have as much pressure as Aztec would.