I really wish DLC characters other than Piranha Plant had Palutena Guidances. I understand there was probably a reason they really couldn't, but still.
It's hard to when you don't know how many DLC characters there will be. And it's unlikely they could bring them back by that point. PP at least had around 2 years to get one. They'd have had to make it in November, right before the game releases. So... not plausible time. It'd be great if they could bring the voice actors back to set up new ones after DLC is over, though. I'd love that. They all deserve ones~
Worth noting that it makes sense as a placeholder, as they did confirm a second pass far after the first one(well after there's any chance the actors would be available). They at most could've had it done for the first pass, but again, it would be done in November, which is when the game was already finished. The chances of the voice actors being still used is pretty... low.
Either way, it's still disappointing. Mewtwo got it worse in 4, but it also wasn't worked on nearly as much during base like PP was from what it appears(and they didn't seem to have actual DLC beyond it planned for a while. Pass 1 was planned at least more than 2 months in advance, which gives them an excuse to make a generic one again. Though actually... did they reuse the lines from 4? If so, then the actors could've been done really early on, like not long after the concept of DLC was confirmed). But yeah, lots of possibities for why it's like that.