But why?
A multitude of reasons, most likely. In part accessibility; rigid class locking for 30+ hour experiences is becoming a thing of the past, as more and more RPGs and ARGs offer the ability to respec. The availability of respeccing varies, but it's more or less become the norm.
The other reason is likely due to the type of game Andromeda is. While the trilogy were fairly tightly contained narrative and gameplay arcs, Andromeda is attempting to emphasise more open play space less linear adventuring with a lot of side content and questing that can be done out of sequence. This includes post-game play, open planet zones, etc. Context and style of combat encounters is likely to vary wildly, and the amount of time a player could spend with a single Ryder playthrough will likely eclipse previous games. Thus the encouragement to leave more tools open to play with in one file versus locking skills off.
This decision may also have been influenced by Mass Effect 3's multiplayer, which is cited as a major influence on Andromeda's combat. In ME3's multiplayer half the excitement came from juggling multiple characters with different skills to try new things. Perhaps BioWare are attempting to translate that to single player.
