If they're changing them this late in the design cycle and almost 6 months after the launch, it's likely because they've tried very hard to make them work, but weren't happy with the results and took a pragmatic decision.
Half of pinside was saying the discs would never work and would potentially ruin the game when announced. Now it's the end of the world that it's being removed for reliability reasons? Come on.
Everyone was wowed by the pitching upper pf ... now the disc was the main feature? Really?
The chest change is definitely a good idea. The machine I played and every time I've seen it streamed there were good shots rejected, some of which would go SDTM. If as he suggests the change fixes this, then I can't see how it's not good.
As for cheaping out ... this remains by far the most ambitious machine since WOZ and still has so much interactive stuff going on. I'd be amazed if a similarly expensive Stern LE was anywhere close to half the BoM - even for the seemingly upgraded Iron Maiden LE. PotC is still the veritable kitchen sink.
Finally, features are cut or scaled back for reliability or cost reasons on all games. You're just actually witnessing the former here because JJP have decided to launch the games and test them publicly for months before they ship. How many machines have been half-arsed engineering or reliability wise lately, or if not physically then with code? Far too many.