Folks are wise to question if they should use OSS that has a CLA assigning copyright because that means they should have zero expectations about the license not changing.
If you look at it from a proprietary software company (which is what Hashicorp is now), it's totally expected and understandable. Why should they spend money supporting extra load on their infrastructure from people that are not directly paying for that? It makes perfect sense.
Is it short-sighed? If you think they will go down in market share from now on, yes. But Hashicorp probably thinks it won't or it wouldn't have made the change in the first place. For them, it's all the way up from here.
Folks are wise to question if they should use OSS that has a CLA assigning copyright because that means they should have zero expectations about the license not changing.