There were no Hoolefoids in the trailer… I think you meant the Tharpods. Also, these species are probably there because, well, borrowing already fitting designs from the PS3 games is much easier than redesigning creatures from the old series so that they look good in the movie. It's a low-budget movie, so it saves a lot of effort.
Tharpods! That's the one! Whoops
And yeah, I guess they're using more recent species for budgetary reasons; but then again, there weren't that many pivotal characters in the original game… they could probably have found a way around the budget and still use Solana species…? I don't know. And, naturally, I can't know without being able to look at the numbers myself (and even if I could see their budget statistics, I'm hardly an expert on budgeting as it is!). I guess all we can do is wait and see how much the Fongoids/Tharpods play into the narrative of the finished movie….
This is the Signature Box. Writing in it means that things will appear under your posts; write as you please, for example: Why not describe the purpose of the Signature Box?