Google forced them to take the Play Store and search widget (including default search engine) as a condition to get Play Services.
Play Services is required by a majority of android apps and developping and maintening a compatible system layer is just out of reach of most(all?) device makers.
You’re asking if Motorola can’t just sell a phone that cannot run most of published android apps out of the box.
> unless an alternative ecosystem is created
That can’t happen while Google is free to do anything to crush potential competitors (they’re also found bullying makers out of bundling stuff like third party stores on their phones, and the chinese makers seem to be the only ones getting away with it), so the only way out is basically to lawsuit the hell out of the situation.