It really depends on how good they are. I'll admit, there's a certain charm to having a well-known celebrity voice a character in a video game, mainly because it shows that video games as a medium are being taken seriously. Like in the original Mass Effect trilogy, on top of voice acting regulars you had a variety of celebrities that all gave good performances such as Seth Green, Yvonne Strahovski, Tricia Helfer, Adam Baldwin, and Martin Sheen, among others.
It helps that while many of the actors could be seen as celebrities, they weren't of the "tabloids for their personal lives kind" of A-listers that TMZ follows and has people obsessing over them like zombies. Rather, people known mostly for their talent and are prolific because of it. One of the complaints about Andromeda was that there were no voice actors that could be considered a celebrity. To be fair though, the lack of well-knowns was the least of that game's problems.
On the other hand, a celebrity voice actor is not a guarantee of a good performance. Fallout: New Vegas had a lot of good talent, but the worst actor was Matthew Perry aka Chandler from Friends. And as mentioned, it's just more expensive. I feel like using celebrities could potentially divert funds that could be used elsewhere. Basically, what I'm saying is: Talent first, name recognition second.