Haha, I never noticed all these points back in 2006.. guess the tight plot standards of today's games have spoiled us!
Especially Boliva's Redux level.. Lara's rage towards Amanda really comes off as projecting her own guilt over herself being the source of her mother's death
It really was Lara who set off the chain reaction and Amanda might have potentially saved the lives of everyone in the vicinity by goading Amelia into pulling out the sword. (Why it would explode if the sword wasn't pulled out is another thing I don't fully understand
Maybe she was aware every Tomb Raider game needs an explosion at the end
)
EDIT- More stuff I just thought about while brushing my teeth!
Lara may have experienced the dais before but compared to Amanda she really didn't know how it worked. Amanda wanted to use it to go to Avalon (in which case.. why didn't she pull out the damn sword herself??) But at the same time Lara wanted to.. travel back in time to save her mother? What did she think would happen if she inserted the sword besides 'getting answers'? She had the opportunity to save her mother right in front of her but instead caused more confusion by yelling out things her mother didn't really understand ("It's Lara, your daughter!" "What? What about my daughter?") Lara really screwed up and wasted both her and Amanda's chances to get what they want.
Also, the dais only working once can make sense plot-wise, but why would the ancient societies go to the trouble to build them and then just let them sit there while they died out? Were they aware they needed Excalibur reforged? How did they even know they were missing pieces?