Great mod. A few thoughts.
- There needs to be a way to reclaim soil. If not, you effectively have a timer on your map.
- Animals should avoid the tiberium. Currently they randomly wander into it, which can be annoying if you forget to set your zones whenever you get new animals.
- The tiberium suit is great, but it is rather boring to have everyone in the same outfit, which also covers them completely.
- Currently you have to manually harvest tiberium since you can't set growing zone on it.
-There will be a way to stop tiberium from growing - not sure about the corrupted soil yet.
-Animals don't know about the dangers of Tiberium - there should be no reason for them to avoid it, as inconvenient as it might be.
-Well you don't have to make all your colonists wear it - it's not for looks, but to be practical and protect some of your colonists, or all if you care that much. Though I understand what you mean.
-You shouldn't be able to grow Tiberium, so no growing zones for that - though you can select multiple crystals with the harvest tool.
Animals shouldn't avoid Tiberium. Visceroids need to come from somewhere.
<--add this *hint: suggestion 
Don't worry - it's all been planned long ago ;P