I'm being a bit glib, but from the point of view of someone who used SFP optics once in a while, it seemed like the whole "standard" was a bit of a mess.

If it was known that vendors would try to push their thermals past what the device cage would support, why not address that better?

The general impression I was given is that thermal loads were one of the primary reasons given for vendor-locking pluggable optics, and that the original SFP spec didn't even address it.