I would love to be able to fix the cracks with plaster. I actually thought that i could do this when played for the first time.
But in my opinion the timing is decent. Playing with friends and seeing those cracks everywhere in August with default start date settings. 1,5-2 months is more than enough for me and my friends to progress and sometimes even get bored depending on the map size, so it's pretty good to see the world changing. The thing that i'm concerned of is the speed that these plants grow and cracks appear. It takes about two in-game weeks to cover the whole GIGAMART wall with cracks and ivy when it just starts happening, which i find quite unrealistic.