Cost-benefit, my good man. Kodiaks shred things on their own; Hoshikos permit them to survive long enough to do so (both by healing them and by shutting down enemy units, in certain circumstances). Cielos help your existing units shred things a little faster, which, if you think about it, is just like adding another few combat ships, regardless. So, if you think about it, either way you're just improving the stopping power of your fleet.
Now, if Embolden provided a boost to ANTIMATTER regen instead of RoF, you'd be in business. The possibility gets me excited just thinking about it.