I read most of the post as it was very long.
For the most part I agree with you (I hate bloat as much as the next guy). However, most of the examples you quoted were for things like web servers, HTML, (perhaps I'm missing one). All of these protocols have no consequences for the entire body of people using these protocols. If a web server in china screws up, it doesn't affect me at all. If someone screws up with bitcoin and sends 2 million coins into the darkness, that affects us all. That can only happen so many times before bitcoin is no longer worth anything to anyone in its current form. It would be nice to be able to run a message through a validator to get some indication of _major_ screw ups. This would not have to be part of your script language.
What validator? The exchange was writing their own custom code. The client wouldn't allow you to make this transaction. When you are working with raw code that is the risks you take.
If you are indicating a miner should validate all scripts that quickly becomes very difficult. The scripting language is very complex and there are many (some not yet even implemented) permutations of possible scripts. What happens when miners start rejecting scripts that are valid but they think aren't valid and your transactions can't find their way into the blocks. Lastly someone may decide they want to destroy currency and retain a public record of this.