It's a stage race dude.
If we want heated action, there are plenty of 1 day races to go around.
I find it absolutely understandable, that the teams ride it this way, it's only day 5 in a 3 week race.
I have been watching GTs for decades and never seen it as bad as today (the stage 2 days ago was also dreadfully passive). There was no point of protest and no super hard preceding day to justify this behaviour, even if logically I fully sympathise with the smaller teams in not participating in such a futile exercise. We arent even anywhere near a rest day with riders on their last legs (as you say, it is only day 5). The best GTs will feel like they contain numerous one day races to sustain interest on days when there is no GC fight. That is completely fundamental to their viability as a mass spectacle.
I suspect it is an attempt by lower budget teams to send a message to Quickstep and LottoJumbo to at least give a breakaway a few minutes lead to create the slightest hint of a contest. I suspect we will see breakaway leads opened to 3-4 mins in the coming days. I also suspect ASO will think twice in future about sprint point placement. Perhaps being so close to the start it demotivated any breakaway hopefuls even further?
If you were satisfied watching this then that is of course fine. But to try and defend it as normal is to re-write history. I am sure most fans, sponsors, TV networks and ASO will not have been satisfied and that there will be discussions behind closed doors to avoid a repeat. Either that or we shorten stages to 15km!