Frankly, that would make sense. Let's be honest, if you want to conquer a planet and use nukes, you HAVE to suffer because of that.
Being able to terraform away the dust would make sense imo.
Also, in my opinion the amount of dust raised by beam weapons should be minimal anyway....
Consider the power of said weapons... this isn't a sci-fi style laser, this is a real combat laser, which means it produces superheating and explosions when it strikes a target. Let alone railguns, which also are 'beams' in terms of this discussion. Terraforming dust makes sense, but beams causing dust also makes a lot of sense.
I am not against ability to terraform dust but consider that it would make beam based bombardment very powerful. Beam bombardment does not radiate the planet so the only medium-term effect is the dust - which can already be counteracted through copious application of infrastructure.
To be fair, beam bombardment is dangerous, MUCH more dangerous then standing off and launching vast numbers of missiles, it's also quite a bit less effective per tonnage involved. Currently planets cannot mount missile weapons, meaning that if your fleet is out of beam range, it's safe. By definition, STOs outrange equal tech ships, that means if you want to use beam weapons, you are risking quite a lot of return fire(and I would be fine with more of a buff of STOs, personally, like letting them have better tracking speeds then the minimum, or more armor). And if there isn't return fire...well...then it's only a matter of time, regardless.
It's not like it normally takes resources to reduce dust, just time. Terraforming is just a way to make that time shorter using resources.