Not being able to chance the member after Act 1 might mean less choices, but it also means you do more meaningful choices with real consequences. IMO that's a good thing.

I still don't like that they are making all party members origin characters you can choose in the beginning. IMO it'd be nice that there are some companions that show up later. For example Act 2 could have 1-3 companions you can pick if you happen to lose one, you have replacements that aren't generic mercenaries you create yourself. Of course it seems like they really want to have similar "godwoken" story where all have same motivation for sticking around, then having companions joining in later would conflict with that.