That's part of what an adaptation is, i.e. the filmmaker's take on the source material.
If they want to do that, then make an original story set in SH based on the source material of "the SH series overall". When you take a specific story and adapt it, most fans expect it to remain as faithful as possible. Because if you wanted and original story with original characters and original themes that have little to nothing to do with the specific source material you picked, then what is the point of even "basing" it on a specific game? Again, my Lord of the Rings comparison. A good deal of fans complain about the already rather tame (imo) changes Peter Jackson made. I'd love to see them react to a LotR movie that got the same treatment as the SH movie...
To each their own, then. After Bassett said that he's doing his own /take/ on it, I was fine with it; it's all about expectations. I'm fine with an adaptation of SH3 as long as they're not promising it to be exactly the same (and having it /not/ be the same afterward). I guess I see it the same as Shattered Memories.