Design is a series of choices and compromises. There needs to be focus on the key requirements, and everything else is secondary.
Given the rise in Apple’s Services revenue, Apple Music in particular, Apple’s sought to make the best speaker for home audio, which Apple regards as coming from Apples’ Music Services. And sticking with the cleanest possible hardware arrangement, Apple’s chosen voice i.e. Siri, as the interaction mechanism.
Consequently, comparisons with the Amazon Echo products are limited and misaligned, as the HomePod is a “Music-First” product.
Apple will iterate and add new features, but at it’s core, the HomePod is for us to listen to it. That HomePod can listen to us is consequence of those design decisions.