The same badges will buy the same level gear, that is correct.

Typically a new raid instance comes out, with higher iLV gear.
And a new pvp season starts, with the same iLV gear.
In both cases, the new highest level stuff has the highest iLV values.

Heroics will typically drop a badge type, which can be used for gear which was previously raid or arena only.
But the same badge type buys the same level of gear as it always did.
You just have access to a higher badge type from the heroics.
And a new higher badge type from raids.