D3's Fusion engine already has blastable/deformable terrain. And destructable brushes in levels. Just not used that much.
That's what the experimental warpcore is for
(have you noticed in every videoclip the Pyro spawns next to a planet, not inside the planet's atmosphere? - maybe the warp mechanism has to avoid strong gravity pulls)
...neither Zeta Aquilae nor Brimspark actually have an atmosphere.
Many space games used to have (and have now) upgrade stores and a merchant/social element.
The feature is there, it works, but it's never been used in the D3 campaign. A weapon has to have a terrain damage value specified in the table.
Scripted environmental destruction is something different entirely. Lots of games (heck I'd say most games) have that.
So what would be really cool would be to include that same kind of realistic environmental destruction WITHOUT having to script it all fall a certain way. Gaming tech, as it happens, is getting real close to doing this.