The new loyalty program does allow one to earn elite nights towards status--we get 1 elite night credit for every 20 room nights consumed. My suspicion is that Marriott may copy SPG and occasionally allow double credits (1 elite night for every 10 room nights consumed) when they determine they need to incentivize this more.
That the new loyalty program no longer allows one to earn more than 10 elite nights based on meetings without rooms is a strategic decision, one almost certainly intended to stop the collusion of people trying to achieve higher status without actually staying at Marriott properties.
That the new loyalty program does not count event and meeting spend towards the calculation of spending towards Ambassador status is also a strategic decision, one likely intended to stop the collusion of event organizers who spend a lot but don't stay a lot at Marriott properties. My guess is that there aren't so many people complaining about this overall since most of those don't stay often enough at Marriott properties that it matters. We are hearing a lot of complaints from a loud minority here, more likely.
For the record, it would help me greatly if Marriott allowed event/meeting spend to count towards the $20K Ambassador spending threshold--but I'll hit it regardless.
For the record, it would help me greatly if Marriott allowed events to continue to earn 10 elite nights--but I'll get 100 nights regardless.
I am sure Marriott has done the calculations and decided how best to achieve the goal number of Ambassador guests it wants with the types of guests it most wants. I'm also sure that Marriott will adjust these rules and thresholds in the coming years as it sees the behavior of the customers it wants to continue to attract to stay at its properties (e.g. those who profit the most) and those from which Marriott doesn't profit as much.